Re: A record of domain name must be name server ?

2014-09-11 Thread Mark Elkins
On Wed, 2014-09-10 at 18:13 -0400, Kevin Darcy wrote:
> No, what I'm saying is that if
> 
> example.com owns an A record 203.0.113.48, and
> www.example.com owns an A record 203.0.113.48, then
> 
> where does 48.113.0.203.in-addr.arpa point?
> 
> Some people will point it at example.com, some will point it at 
> www.example.com. What you get is a mish-mosh. No consistency.

Although I prefer the use of a CNAME solution (CNAME www.example.com to
example.com), in the case of separate A (and ) records, one could
point the reverse to both names. Nothing wrong with a PTR record having
more than one answer. There is then no inconsistency, just choice. After
all, pretty much every NS record has at least two Right-Hand-Sides
(Answers)


> If, on the other hand, www.example.com is a CNAME to example.com, then 
> it's crystal clear where the reverse record will point -- example.com. 
> There is no ambiguity or option for inconsistency.
> 
>  - Kevin
> 
> On 9/10/2014 5:48 PM, Eliezer Croitoru wrote:
> > Hey Kevin,
> >
> > This is not an issue at all.
> > A PTR is different then a "A" record and can be used by two reverse 
> > domain names and only the owner of the IP addresses space can define 
> > them.
> > I am not sure if two PTR records for two domains will be applied to 
> > one IP but it is possible for two IP addresses to have the same PTR.
> >
> > Can we even use a CNAME as a PTR???
> >
> > Eliezer
> >
> > On 09/11/2014 12:37 AM, Kevin Darcy wrote:
> >> Also, have you considered the forward/reverse ambiguity that arises when
> >> multiple owner names resolve to the same address? To which of those
> >> names does the PTR point?
> >>
> >>  - Kevin
> >
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Re: A record of domain name must be name server ?

2014-09-11 Thread Matus UHLAR - fantomas

On 10.09.14 18:13, Kevin Darcy wrote:

No, what I'm saying is that if

example.com owns an A record 203.0.113.48, and
www.example.com owns an A record 203.0.113.48, then

where does 48.113.0.203.in-addr.arpa point?


Completely your decision.
Some people will point it at example.com, some will point it at 
www.example.com. What you get is a mish-mosh. No consistency.


Do not mix multiple A and PTR. they are just different things.
You are creating issues where there are none.

If, on the other hand, www.example.com is a CNAME to example.com, 
then it's crystal clear where the reverse record will point -- 
example.com. There is no ambiguity or option for inconsistency.


If you point www CNAME @, the 'www' will have both MX and NS records same as
example.com.  Which may e.g. cause rejectd on backup MX hosts, apparently
not designed to receive mail for www.example.com.

The same applies for all other RRs for exmaple.com Alan named crap.
And that's why I also think it's better to define 'www' as A record, not as
CNAME

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Re: A record of domain name must be name server ?

2014-09-11 Thread Antonio Querubin

On Thu, 11 Sep 2014, Matus UHLAR - fantomas wrote:


If you point www CNAME @, the 'www' will have both MX and NS records same as
example.com.  Which may e.g. cause rejectd on backup MX hosts, apparently
not designed to receive mail for www.example.com.


Actually no.  All other RRs are supposed to be ignored (except for RRSIG, 
etc) once the CNAME exists.  Ie. the MX and NS RRs exist only for 
example.com, but not www.example.com.


Antonio Querubin
e-mail:  t...@lavanauts.org
xmpp:  antonioqueru...@gmail.com
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Promoting slave to master DNS server with dynamic updates

2014-09-11 Thread Eric.BERTHIAUME.external
Hello DNS gurus,

New on the list, I’ve been tasked by my manager to revamp our dns 
infrastructure.  I think this list is the best place to get answers.

Bind 9.3.6-16 running on RHEL5.7

Right now everything run’s on manually editing zone files but we have recently 
integrated vmware orchestrator (automatic deployment of linux vm’s) in the mix 
and that complicates things for automated processes.  Add Autosys to this and 
you have one big messy DNS infrastructure and of course no team wants to change 
their work flows (classic).

So I’ve written a basic script that would allow everyone (admin’s, vmware, 
autosys) to use dynamic updates with nsupdate for all tasks.  Everything works 
dandy but a simple question remains:

If the primary goes down for whatever reason, how can we quickly continue to 
update our DNS records on the secondary?  What are the options?


-  Classic slave/master change manually editing the named.conf?  What 
happens to everything in the jnl file on the master if it crashes before the 
dump and zone transfer?  Lost?

-  Nsupdate special ninja trick?  Read something about updating the SOA 
through dynamic update but didn’t fully understand that process.

-  Pray that we get the primary up?

The last option would normally be the logical choice but like I said our DNS 
infrastructure is a mess and those autosys process control DNS records for 
their “failover” feature (yeah I know) so we need a super-lightning-fast switch 
if we do not want production to stop.

Of course the best solution would be something automatic but I haven’t seen 
anything anywhere.  If it’s manual so be it maybe I would be able to write a 
script that could be used by support and minimize human errors.
I’m already at least pushing for a more recent bind version and of course if a 
special feature exist (maybe I’ve missed it) that provides an easier solution 
that would be a super argument to push for something with more features.

Thanks in advance.

Eric

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Re: A record of domain name must be name server ?

2014-09-11 Thread Sam Wilson
In article ,
 Alan Clegg  wrote:

> On 9/10/14, 8:42 AM, Sam Wilson wrote:
> 
> > And you could reduce maintenance very slightly by replacing
> > 
> > www in  A   75.100.245.133
> > 
> > with 
> > 
> > www in  CNAME   @
> 
> And now you have an MX record, 3 NS records and a bunch of other crap
> associated with the WWW address.  Keeping track of one extra A record
> (and associated  record if you go in that direction) isn't a bad thing.

And the discussion went on from there.  Sorry, I really didn't mean to 
poke a hornets' nest.

> (Personal preferences, of course)

Personal preference and dependent on the exact needs of the users of the 
data, of course.

Sam

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Re: A record of domain name must be name server ?

2014-09-11 Thread Sam Wilson
In article ,
 Antonio Querubin  wrote:

> On Thu, 11 Sep 2014, Matus UHLAR - fantomas wrote:
> 
> > If you point www CNAME @, the 'www' will have both MX and NS records same as
> > example.com.  Which may e.g. cause rejectd on backup MX hosts, apparently
> > not designed to receive mail for www.example.com.
> 
> Actually no.  All other RRs are supposed to be ignored (except for RRSIG, 
> etc) once the CNAME exists.  Ie. the MX and NS RRs exist only for 
> example.com, but not www.example.com.

I think that's a misunderstanding of what Matus wrote.  With separate A 
records then www.example.com will only have an A record.  If you alias 
www to @ then looking up MX and NS records for www will return the ones 
for example.com.

Sam

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Re: Promoting slave to master DNS server with dynamic updates

2014-09-11 Thread John Miller
Hi Eric,

Depends on how long you can live without dynamic updates, and how many
dynamic updates it's acceptable to lose in the event of a master failure.
Journal files are synced every 15 minutes, so in the event of a master
failure (in a single-master situation), you've lost at most 15 minutes'
worth of updates.  Stand up a new master (with config management software,
doable in a few minutes), and you're good to go.

But why have just a single master?  If you're worried about the primary
going down, just have a warm standby ready to go.  To keep zone data in
sync, you could use shared storage, a replicated database (BIND does
support a database backend), or perhaps some sort of also-notify
configuration.  To do the failover itself, you could use something like
Pacemaker/Corosync, ucarp, or similar.  Just pass a VIP back/forth between
the two -- your NS records would only use the VIP.

The big issue I see with converting a slave to a master is that you'd have
to change all of your zone definitions, change your named.conf, and do so
under time pressure.  Then, when the master came back online, you'd have to
change your zone definitions again.  With config management software, not
that hard to do, but servers are cheap these days -- easier just to create
a failover pair (or group) for your master, then stand up as many slaves
(doing update forwarding) as you need.  If you purchase a DNS appliance
(Infoblox, SolidServer, Bluecat, etc.), this is how they handle things.

Separate issue: you might think about trying out RHEL 6 -- it's using a
much newer version of BIND which has some updated tools (particularly rndc
freeze/thaw, HTTP stats interface).

John

On Thu, Sep 11, 2014 at 4:48 AM, 
wrote:

> Hello DNS gurus,
>
>
>
> New on the list, I’ve been tasked by my manager to revamp our dns
> infrastructure.  I think this list is the best place to get answers.
>
>
>
> Bind 9.3.6-16 running on RHEL5.7
>
>
>
> Right now everything run’s on manually editing zone files but we have
> recently integrated vmware orchestrator (automatic deployment of linux
> vm’s) in the mix and that complicates things for automated processes.  Add
> Autosys to this and you have one big messy DNS infrastructure and of course
> no team wants to change their work flows (classic).
>
>
>
> So I’ve written a basic script that would allow everyone (admin’s, vmware,
> autosys) to use dynamic updates with nsupdate for all tasks.  Everything
> works dandy but a simple question remains:
>
>
>
> If the primary goes down for whatever reason, how can we quickly continue
> to update our DNS records on the secondary?  What are the options?
>
>
>
> -  Classic slave/master change manually editing the named.conf?
> What happens to everything in the jnl file on the master if it crashes
> before the dump and zone transfer?  Lost?
>
> -  Nsupdate special ninja trick?  Read something about updating
> the SOA through dynamic update but didn’t fully understand that process.
>
> -  Pray that we get the primary up?
>
>
>
> The last option would normally be the logical choice but like I said our
> DNS infrastructure is a mess and those autosys process control DNS records
> for their “failover” feature (yeah I know) so we need a
> super-lightning-fast switch if we do not want production to stop.
>
>
>
> Of course the best solution would be something automatic but I haven’t
> seen anything anywhere.  If it’s manual so be it maybe I would be able to
> write a script that could be used by support and minimize human errors.
>
> I’m already at least pushing for a more recent bind version and of course
> if a special feature exist (maybe I’ve missed it) that provides an easier
> solution that would be a super argument to push for something with more
> features.
>
>
>
> Thanks in advance.
>
>
>
> Eric
>
>
>
> **
> Ce courrier électronique, y compris les pièces jointes, est à l'attention
> exclusive des destinataires désignés et revêt un caractère confidentiel.
> Si vous recevez ce courrier électronique par erreur, merci d'en informer
> sans délai l'expéditeur et de supprimer son contenu et ses pièces jointes.
>
> Le contenu de ce courrier électronique ne pourrait engager la
> responsabilité de la Banque de France que s'il a été émis par une personne
> dûment habilitée agissant dans le strict cadre des fonctions auxquelles
> elle est employée et à des fins non étrangères à ses attributions.
>
> L'expéditeur de ce courrier électronique ne peut pas garantir la sécurité
> de l'acheminement par voie électronique et ne saurait dès lors encourir une
> quelconque responsabilité en cas d'altération de son contenu.
>
> **
>
> This e-mail, attachments included, is intended solely for the addressees
> and should be considered as confidential.
> Should you receive this message by error, please notify the sender
> immediately and destroy this

Re: A record of domain name must be name server ?

2014-09-11 Thread Kevin Darcy

On 9/11/2014 3:47 AM, Matus UHLAR - fantomas wrote:

On 10.09.14 18:13, Kevin Darcy wrote:

No, what I'm saying is that if

example.com owns an A record 203.0.113.48, and
www.example.com owns an A record 203.0.113.48, then

where does 48.113.0.203.in-addr.arpa point?


Completely your decision.
Some people will point it at example.com, some will point it at 
www.example.com. What you get is a mish-mosh. No consistency.


Do not mix multiple A and PTR. they are just different things.
You are creating issues where there are none.
The issue is consistency. If you give admins choices where to point a 
PTR, and the RFCs don't provide any clear guidance, you're going to get 
inconsistent results.


If you make "www" a CNAME to apex, then the RFCs are clear that you 
can't point the PTR to the "www" name. The *only*legal*choice* is to 
point the PTR at the apex name. You're going to get *much*more* 
consistent results.


Consistency is a good thing, isn't it? Sure, the earth isn't going to 
fall off its axis of rotation just because of the way people point their 
A and PTR records, CNAME or don't CNAME. But if we can nudge people in 
the direction of consistency, and there is no downside, why wouldn't we 
do that? That's what "best practices" are all about -- impelling people 
towards processes/methods/conventions that ultimately benefit 
*everyone*. Greatest good for the greatest number, and all that.


If, on the other hand, www.example.com is a CNAME to example.com, 
then it's crystal clear where the reverse record will point -- 
example.com. There is no ambiguity or option for inconsistency.


If you point www CNAME @, the 'www' will have both MX and NS records 
same as

example.com.  Which may e.g. cause rejectd on backup MX hosts, apparently
not designed to receive mail for www.example.com.
So, is it better that mail sent erroneously to www.example.com fall 
through the RFC 5321 algorithm and attempt to be delivered to the A 
record? That host is almost certainly is a *web* server and quite likely 
to not even be listening on port 25. After some period of time, the user 
ultimately gets a "connection timed out, still retrying" NDR and 
scratches their head trying to figure out what went wrong. Meanwhile, 
the sending MTA keeps on retrying, web server sees "garbage" traffic on 
an off-port and generates ICMP packets back to the source. In the "CNAME 
to @" scenario, at least the mail gets rejected promptly by a *mail* 
server, you have a nice clear audit trail on the server side and a 
meaningful error message (e.g. "I don't accept mail for the 
www.example.com domain") back to the user.


(Yes, I'm aware that there was a proposal recently discussed on the 
DNSOP list for an MX-target convention to denote "no mail service 
offered here". That would presumably solve the problem I cited in the 
previous paragraph. But AFAIK that proposal is many years away from 
widespread adoption, and even if adopted, it puts an extra burden on the 
DNS admins to populate the "no service" MX record, which, again, is 
going to produce inconsistent results -- some admins will remember to do 
it; many won't).


Obviously, if one wants mail for example.com and www.example.com to be 
delivered to *different* MX targets, then "CNAME to @" isn't an option. 
But in the general case, where you don't want mail to www.example.com to 
be deliverable *at*all*, "CNAME to @" is quite a viable option; 
arguably, a *better* option, since the failure mode is faster and 
cleaner than directing MTAs to try to deliver mail, as per RFC 5321, to 
a web server.




The same applies for all other RRs for exmaple.com Alan named crap.

Actually, the only other RR type that Alan enumerated specifically was 
NS, which operates on entirely different principles, and serves a 
significantly different function, than MX-based mail routing. Who would 
be looking up www.example.com with QTYPE=NS? Is that even a plausible 
use-case scenario?


What other RR types do you have in mind? SRV records? They have their 
own defined naming structure, which effectively precludes apex naming. 
TXT records used for SPF purposes? Worst case for that is that the same 
hosts trusted to send mail for example.com are also trusted to send mail 
for www.example.com -- but *sending* mail servers are presumably under 
the control (directly or indirectly) of the domain owner, so the 
potential for negative fallout seems rather minimal. Something else? Are 
you thinking that a LOC record should be differentiated between "www" 
and apex, if the web server is physically in a different datacenter than 
the corporate headquarters of the domain owner?


- Kevin

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Re: A record of domain name must be name server ?

2014-09-11 Thread Kevin Darcy

Mark,
Depending on implementation, a PTR RRset with multiple 
records either


-- only ever gets answered with the "first" record of the set (in which 
case the second and subsequent records of the set are just a waste of 
space), or
-- answers in a random, cyclic and/or round-robin fashion (in which 
case, the results are non-deterministic from the standpoint of a client, 
and this can cause problems and/or confusion)


So, although the standards allow multiple RRs, in practical terms, it 
only makes sense for a PTR RRset to contain a *single* RR.


- Kevin

On 9/11/2014 3:45 AM, Mark Elkins wrote:

On Wed, 2014-09-10 at 18:13 -0400, Kevin Darcy wrote:

No, what I'm saying is that if

example.com owns an A record 203.0.113.48, and
www.example.com owns an A record 203.0.113.48, then

where does 48.113.0.203.in-addr.arpa point?

Some people will point it at example.com, some will point it at
www.example.com. What you get is a mish-mosh. No consistency.

Although I prefer the use of a CNAME solution (CNAME www.example.com to
example.com), in the case of separate A (and ) records, one could
point the reverse to both names. Nothing wrong with a PTR record having
more than one answer. There is then no inconsistency, just choice. After
all, pretty much every NS record has at least two Right-Hand-Sides
(Answers)



If, on the other hand, www.example.com is a CNAME to example.com, then
it's crystal clear where the reverse record will point -- example.com.
There is no ambiguity or option for inconsistency.

  - Kevin

On 9/10/2014 5:48 PM, Eliezer Croitoru wrote:

Hey Kevin,

This is not an issue at all.
A PTR is different then a "A" record and can be used by two reverse
domain names and only the owner of the IP addresses space can define
them.
I am not sure if two PTR records for two domains will be applied to
one IP but it is possible for two IP addresses to have the same PTR.

Can we even use a CNAME as a PTR???

Eliezer

On 09/11/2014 12:37 AM, Kevin Darcy wrote:

Also, have you considered the forward/reverse ambiguity that arises when
multiple owner names resolve to the same address? To which of those
names does the PTR point?

  - Kevin

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Re: A record of domain name must be name server ?

2014-09-11 Thread Mark Elkins
On Thu, 2014-09-11 at 11:27 -0400, Kevin Darcy wrote:
> Mark,
> Depending on implementation, a PTR RRset with multiple
> records either
> 
> -- only ever gets answered with the "first" record of the set (in
> which case the second and subsequent records of the set are just a
> waste of space), or
> -- answers in a random, cyclic and/or round-robin fashion (in which
> case, the results are non-deterministic from the standpoint of a
> client, and this can cause problems and/or confusion)


Last time I checked, ALL matching records are returned as a single
Resource Record Set - (and in the case of DNSSEC - covered with a single
signature).

What the receiver does with it is up to that receiver... as you say -
some of the information may be discarded.

> So, although the standards allow multiple RRs, in practical terms, it
> only makes sense for a PTR RRset to contain a *single* RR.

I would still disagree. When there is forward<-->reverse checking, one
may need the complete answer. I certainly have some processes that do an
exhaustive check.


- Kevin
> 
> On 9/11/2014 3:45 AM, Mark Elkins wrote:
> 
> > On Wed, 2014-09-10 at 18:13 -0400, Kevin Darcy wrote:
> > > No, what I'm saying is that if
> > > 
> > > example.com owns an A record 203.0.113.48, and
> > > www.example.com owns an A record 203.0.113.48, then
> > > 
> > > where does 48.113.0.203.in-addr.arpa point?
> > > 
> > > Some people will point it at example.com, some will point it at 
> > > www.example.com. What you get is a mish-mosh. No consistency.
> > Although I prefer the use of a CNAME solution (CNAME www.example.com to
> > example.com), in the case of separate A (and ) records, one could
> > point the reverse to both names. Nothing wrong with a PTR record having
> > more than one answer. There is then no inconsistency, just choice. After
> > all, pretty much every NS record has at least two Right-Hand-Sides
> > (Answers)
> > 
> > 
> > > If, on the other hand, www.example.com is a CNAME to example.com, then 
> > > it's crystal clear where the reverse record will point -- example.com. 
> > > There is no ambiguity or option for inconsistency.
> > > 
> > >  - Kevin
> > > 
> > > On 9/10/2014 5:48 PM, Eliezer Croitoru wrote:
> > > > Hey Kevin,
> > > > 
> > > > This is not an issue at all.
> > > > A PTR is different then a "A" record and can be used by two reverse 
> > > > domain names and only the owner of the IP addresses space can define 
> > > > them.
> > > > I am not sure if two PTR records for two domains will be applied to 
> > > > one IP but it is possible for two IP addresses to have the same PTR.
> > > > 
> > > > Can we even use a CNAME as a PTR???
> > > > 
> > > > Eliezer
> > > > 
> > > > On 09/11/2014 12:37 AM, Kevin Darcy wrote:
> > > > > Also, have you considered the forward/reverse ambiguity that arises 
> > > > > when
> > > > > multiple owner names resolve to the same address? To which of those
> > > > > names does the PTR point?
> > > > > 
> > > > >  - Kevin
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RE: Promoting slave to master DNS server with dynamic updates

2014-09-11 Thread Eric.BERTHIAUME.external
Hello John,

Thanks for taking the time to respond.

For the journal files could i force the dump every time i do an update ?  
nsupdate… rndc freeze/thaw boom everything in sync.   I know that normaly you 
wait 15 minutes and that bind does that for you but we do not have that much 
load and it would provide us with a safety net regarding a crash?  But then 
again I’m pretty confident a 15 minutes lost of update data is acceptable for 
production.

For your main solution let me get this…

My master with VIP gets the dynamic updates and since I have an also-notify 
configured he pushes the updates to my warm-stand-by server running a named in 
what mode?  Master also?   But since no one has this server configured as a 
resolver he doesn’t get requested until I flip the VRRP VIP and restart bind?  
That could very well work for us BUT what if I want to push an update to this 
“warm stand-by server”?  Since he’s also a master it should work no?  And 
resyncing back to first master……. This is not an easy one if we do not use 
shared storage.

To be able to use a backend database I would have to upgrade my bind version 
no?  It’s why people use the new map format?  I’m pushing for it (want 
named-journalprint from 9.8 tools) and it would be nice but I’m afraid the 
support team will have an heart attack from too many changes at the same time 
(it’s a government organization so it’ss w sooo).  That is 
also why we are running on RHEL5.7 and not 6 even if every new server deployed 
is on RHEL6.3.

They are planning Infoblox appliances (I’m actually using those on another 
project) but since it’s the production servers it might take at least a year 
before they start the project.  Dynamic updates prepares this so their world 
will not fall apart in one shot.

Puppet is used but only on non-system related config… so I would have a tough 
time for them to accept this but at least I’m advancing towards my goals ☺

Thanks.

Eric


De : John Miller [mailto:johnm...@brandeis.edu]
Envoyé : jeudi 11 septembre 2014 17:02
À : BERTHIAUME Eric (UA 2148)
Objet : Re: Promoting slave to master DNS server with dynamic updates

Hi Eric,
Depends on how long you can live without dynamic updates, and how many dynamic 
updates it's acceptable to lose in the event of a master failure.  Journal 
files are synced every 15 minutes, so in the event of a master failure (in a 
single-master situation), you've lost at most 15 minutes' worth of updates.  
Stand up a new master (with config management software, doable in a few 
minutes), and you're good to go.

But why have just a single master?  If you're worried about the primary going 
down, just have a warm standby ready to go.  To keep zone data in sync, you 
could use shared storage, a replicated database (BIND does support a database 
backend), or perhaps some sort of also-notify configuration.  To do the 
failover itself, you could use something like Pacemaker/Corosync, ucarp, or 
similar.  Just pass a VIP back/forth between the two -- your NS records would 
only use the VIP.
The big issue I see with converting a slave to a master is that you'd have to 
change all of your zone definitions, change your named.conf, and do so under 
time pressure.  Then, when the master came back online, you'd have to change 
your zone definitions again.  With config management software, not that hard to 
do, but servers are cheap these days -- easier just to create a failover pair 
(or group) for your master, then stand up as many slaves (doing update 
forwarding) as you need.  If you purchase a DNS appliance (Infoblox, 
SolidServer, Bluecat, etc.), this is how they handle things.
Separate issue: you might think about trying out RHEL 6 -- it's using a much 
newer version of BIND which has some updated tools (particularly rndc 
freeze/thaw, HTTP stats interface).
John

On Thu, Sep 11, 2014 at 4:48 AM, 
mailto:eric.berthiaume.exter...@banque-france.fr>>
 wrote:
Hello DNS gurus,

New on the list, I’ve been tasked by my manager to revamp our dns 
infrastructure.  I think this list is the best place to get answers.

Bind 9.3.6-16 running on RHEL5.7

Right now everything run’s on manually editing zone files but we have recently 
integrated vmware orchestrator (automatic deployment of linux vm’s) in the mix 
and that complicates things for automated processes.  Add Autosys to this and 
you have one big messy DNS infrastructure and of course no team wants to change 
their work flows (classic).

So I’ve written a basic script that would allow everyone (admin’s, vmware, 
autosys) to use dynamic updates with nsupdate for all tasks.  Everything works 
dandy but a simple question remains:

If the primary goes down for whatever reason, how can we quickly continue to 
update our DNS records on the secondary?  What are the options?


-  Classic slave/master change manually editing the named.conf?  What 
happens to everything in the jnl file on the master if it crashes before the 
dump and zon

Re: A record of domain name must be name server ?

2014-09-11 Thread Matus UHLAR - fantomas

On 9/11/2014 3:47 AM, Matus UHLAR - fantomas wrote:

On 10.09.14 18:13, Kevin Darcy wrote:

No, what I'm saying is that if

example.com owns an A record 203.0.113.48, and
www.example.com owns an A record 203.0.113.48, then

where does 48.113.0.203.in-addr.arpa point?


Completely your decision.
Some people will point it at example.com, some will point it at 
www.example.com. What you get is a mish-mosh. No consistency.


Do not mix multiple A and PTR. they are just different things.
You are creating issues where there are none.


On 11.09.14 11:20, Kevin Darcy wrote:
The issue is consistency. If you give admins choices where to point a 
PTR, and the RFCs don't provide any clear guidance, you're going to 
get inconsistent results.


sorry, but again - you are searching for consistency somewhere, where no
consistency (nor a PTR) is required.

Consistency is a good thing, isn't it? Sure, the earth isn't going to 
fall off its axis of rotation just because of the way people point 
their A and PTR records, CNAME or don't CNAME. But if we can nudge 
people in the direction of consistency, and there is no downside, why 
wouldn't we do that? That's what "best practices" are all about -- 
impelling people towards processes/methods/conventions that 
ultimately benefit *everyone*. Greatest good for the greatest number, 
and all that.


I haven't met a case where this level of "consistency" would be needed.
I have met a case where the "only one A should point to an IP" caused
troubles.

your argument fails immediately when there's need for more than just A on
www.example.com

(Yes, I'm aware that there was a proposal recently discussed on the 
DNSOP list for an MX-target convention to denote "no mail service 
offered here". That would presumably solve the problem I cited in the 
previous paragraph. But AFAIK that proposal is many years away from 
widespread adoption, and even if adopted, it puts an extra burden on 
the DNS admins to populate the "no service" MX record, which, again, 
is going to produce inconsistent results -- some admins will remember 
to do it; many won't).


... and this is just example of it.


The same applies for all other RRs for exmaple.com Alan named crap.

Actually, the only other RR type that Alan enumerated specifically 
was NS, which operates on entirely different principles, and serves a 
significantly different function, than MX-based mail routing. Who 
would be looking up www.example.com with QTYPE=NS? Is that even a 
plausible use-case scenario?


well, me and Alan have shown examples why "www CNAME @" is not a good idea.
we both also said it's personal preference.

What other RR types do you have in mind? 


Does it matter at all? It _may_ happen, and it's the case where CNAME is
not usable.

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Re: A record of domain name must be name server ?

2014-09-11 Thread Kevin Darcy

On 9/11/2014 12:08 PM, Matus UHLAR - fantomas wrote:

On 9/11/2014 3:47 AM, Matus UHLAR - fantomas wrote:

On 10.09.14 18:13, Kevin Darcy wrote:

No, what I'm saying is that if

example.com owns an A record 203.0.113.48, and
www.example.com owns an A record 203.0.113.48, then

where does 48.113.0.203.in-addr.arpa point?


Completely your decision.
Some people will point it at example.com, some will point it at 
www.example.com. What you get is a mish-mosh. No consistency.


Do not mix multiple A and PTR. they are just different things.
You are creating issues where there are none.


On 11.09.14 11:20, Kevin Darcy wrote:
The issue is consistency. If you give admins choices where to point a 
PTR, and the RFCs don't provide any clear guidance, you're going to 
get inconsistent results.


sorry, but again - you are searching for consistency somewhere, where no
consistency (nor a PTR) is required.

Consistency is a good thing, isn't it? Sure, the earth isn't going to 
fall off its axis of rotation just because of the way people point 
their A and PTR records, CNAME or don't CNAME. But if we can nudge 
people in the direction of consistency, and there is no downside, why 
wouldn't we do that? That's what "best practices" are all about -- 
impelling people towards processes/methods/conventions that 
ultimately benefit *everyone*. Greatest good for the greatest number, 
and all that.


I haven't met a case where this level of "consistency" would be needed.
Needed? Is that where you're setting the bar here? A little too high, 
I'd say. My point is that consistency is a good thing, and the "CNAME to 
@" practice helps to foster that. Whether it's *needed* would be a whole 
other question. Somewhere between "necessary" and (what Alan called) 
"preferences" are these things called recommendations or best practices.




I have met a case where the "only one A should point to an IP" caused
troubles.
Well, sure. Some names, such as zone-apex names, *cannot* own CNAME 
records. If example1.com and example2.com need to resolve to the same 
IP, then, and assuming they are both zone-apex names, you're going to 
have multiple As with the same RDATA, and a reverse-record ambiguity. 
That's unavoidable. All I'm saying, is that in the normal case, where 
you have an option, "CNAME to @" makes a lot of sense and should be 
followed.


your argument fails immediately when there's need for more than just A on
www.example.com
If the RDATA needs to be *different* between "www" and apex, or the 
application/subsystem which accesses the resource makes a distinction 
between canonical names and aliases, sure. I'm not laying down a 
hard-and-fast rule. Of course there will be exceptions, where the 
higher-level protocols or the user requirements demand it.


(Yes, I'm aware that there was a proposal recently discussed on the 
DNSOP list for an MX-target convention to denote "no mail service 
offered here". That would presumably solve the problem I cited in the 
previous paragraph. But AFAIK that proposal is many years away from 
widespread adoption, and even if adopted, it puts an extra burden on 
the DNS admins to populate the "no service" MX record, which, again, 
is going to produce inconsistent results -- some admins will remember 
to do it; many won't).


... and this is just example of it.
An example of what? Of what bad things can happen when (semi-)important 
things are left to mere "preference"?



The same applies for all other RRs for exmaple.com Alan named crap.

Actually, the only other RR type that Alan enumerated specifically 
was NS, which operates on entirely different principles, and serves a 
significantly different function, than MX-based mail routing. Who 
would be looking up www.example.com with QTYPE=NS? Is that even a 
plausible use-case scenario?


well, me and Alan have shown examples why "www CNAME @" is not a good 
idea.
Alan's concern was that the "www" name could get associated with record 
types that the DNS admin might not have expected. This is not a problem 
for a competent admin, who will have realistic expectations and an 
understanding of CNAME mechanics. You raised the possibility that a mail 
server might reject messages sent erroneously to "www" and I responded 
that if it's going to fail anyway, at least that failure mode is better 
than a mail server trying to deliver mail to a web server (which is what 
happens in the same scenario when "www" is an independent A record).


You got anything else?


we both also said it's personal preference.
And I'm saying that's a cop-out. It should be a recommended practice -- 
except where there are special mitigating circumstances which make it 
inappropriate or unworkable -- not merely a "preference". Hair styles 
and musical genres are "preferences"; encouraging consistent 
forward/reverse mappings is something that all DNS admins have a stake 
in, whether they realize it or not.




What other RR types do you have in mind? 


Does it matter at all? It _ma

Re: A record of domain name must be name server ?

2014-09-11 Thread Matus UHLAR - fantomas

On 9/11/2014 12:08 PM, Matus UHLAR - fantomas wrote:

we both also said it's personal preference.


On 11.09.14 12:53, Kevin Darcy wrote:
And I'm saying that's a cop-out. It should be a recommended practice 


encouraging consistent 
forward/reverse mappings is something that all DNS admins have a 
stake in, whether they realize it or not.


correct reverse-forward mappings - yes.
correct forward-reverse mappings - no.

In zones apexes it's sometimes just impossible and I have already met people
uselessly insisting on such (pardon me) shit without understanding real
(and potentially much bigger) problem.

It's not usable where it's not usable, of course. But, where it *is* 
usable, I'm just saying it's recommended,


It's definitely not recommended by me. You are of course free to recommend
what you choose, but I think I should warn you I'll oppose that...

Did you seriously think I'd recommend 
something that *doesn't*work*? Please, give me a little more credit 
than that.


I remember you from your postings here, so I really don't think you are
incompetent, especially not an idiot :-)

I just don't agree with this point, because I have already met people not
getting this properly and insisting on something that was likely to get them
into troubles bigger than with having multiple A's...

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Re: A record of domain name must be name server ?

2014-09-11 Thread Bob Harold
In reference to the question of using a CNAME or A record for "
www.example.com", it seems to me that the best solution, if we could ever
get there, would be to create a new record type that means "redirect an A
or  lookup to this other name".  Like this:

example.com.  IN  SOA  
example.com.  IN  ANAME  my.webhosting.com.
www.example.com.  IN  CNAME  my.webhosting.com.

I use "ANAME" to mean "like a CNAME, but only for A and  lookups", with
no restrictions on other names with the same left side (except perhaps
other A and  records if that is necessary for technical reasons).

Several DNS and hosting providers provide similar functionality, but is
there any chance of widespread DNS support for something like this?

Is there already and RFC for this?

I find these interesting sites:
http://www.dnsmadeeasy.com/services/aname-records/
http://aws.amazon.com/route53/faqs/#Supported_DNS_record_types
http://blog.andrewallen.co.uk/2012/06/27/cname-is-out-hello-aname/
(This last one points out a problem with the current implementations - I
think proper support in the DNS protocol would solve this.)

-- 
Bob Harold
DNS and DHCP
University of Michigan
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Re: A record of domain name must be name server ?

2014-09-11 Thread Kevin Darcy

On 9/11/2014 11:51 AM, Mark Elkins wrote:

On Thu, 2014-09-11 at 11:27 -0400, Kevin Darcy wrote:

Mark,
 Depending on implementation, a PTR RRset with multiple
records either

-- only ever gets answered with the "first" record of the set (in
which case the second and subsequent records of the set are just a
waste of space), or
-- answers in a random, cyclic and/or round-robin fashion (in which
case, the results are non-deterministic from the standpoint of a
client, and this can cause problems and/or confusion)


Last time I checked, ALL matching records are returned as a single
Resource Record Set - (and in the case of DNSSEC - covered with a single
signature).

What the receiver does with it is up to that receiver... as you say -
some of the information may be discarded.
If the invoker is using the classic gethostbyaddr() interface, then 
it'll only see the RDATA from the "first" PTR RR, where "first" is 
determined by the local nameserver implementation and/or the local 
Operating System interface for name resolution.



So, although the standards allow multiple RRs, in practical terms, it
only makes sense for a PTR RRset to contain a *single* RR.

I would still disagree. When there is forward<-->reverse checking, one
may need the complete answer. I certainly have some processes that do an
exhaustive check.
Certainly if one gets down to the resolver-library level and grovels 
through all of the RRs in the Answer Section of the response packet, one 
could certainly care more than the typical reverse-resolving 
app/subsystem would. And any software that builds up certain heightened 
expectations is likely to complain if those expectations are not met.


- Kevin

On 9/11/2014 3:45 AM, Mark Elkins wrote:


On Wed, 2014-09-10 at 18:13 -0400, Kevin Darcy wrote:

No, what I'm saying is that if

example.com owns an A record 203.0.113.48, and
www.example.com owns an A record 203.0.113.48, then

where does 48.113.0.203.in-addr.arpa point?

Some people will point it at example.com, some will point it at
www.example.com. What you get is a mish-mosh. No consistency.

Although I prefer the use of a CNAME solution (CNAME www.example.com to
example.com), in the case of separate A (and ) records, one could
point the reverse to both names. Nothing wrong with a PTR record having
more than one answer. There is then no inconsistency, just choice. After
all, pretty much every NS record has at least two Right-Hand-Sides
(Answers)



If, on the other hand, www.example.com is a CNAME to example.com, then
it's crystal clear where the reverse record will point -- example.com.
There is no ambiguity or option for inconsistency.

  - Kevin

On 9/10/2014 5:48 PM, Eliezer Croitoru wrote:

Hey Kevin,

This is not an issue at all.
A PTR is different then a "A" record and can be used by two reverse
domain names and only the owner of the IP addresses space can define
them.
I am not sure if two PTR records for two domains will be applied to
one IP but it is possible for two IP addresses to have the same PTR.

Can we even use a CNAME as a PTR???

Eliezer

On 09/11/2014 12:37 AM, Kevin Darcy wrote:

Also, have you considered the forward/reverse ambiguity that arises when
multiple owner names resolve to the same address? To which of those
names does the PTR point?

  - Kevin

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Re: A record of domain name must be name server ?

2014-09-11 Thread Thomas Schulz
> On 9/11/2014 11:51 AM, Mark Elkins wrote:
>> On Thu, 2014-09-11 at 11:27 -0400, Kevin Darcy wrote:
>>> Mark,
>>>  Depending on implementation, a PTR RRset with multiple
>>> records either
>>>
>>> -- only ever gets answered with the "first" record of the set (in
>>> which case the second and subsequent records of the set are just a
>>> waste of space), or
>>> -- answers in a random, cyclic and/or round-robin fashion (in which
>>> case, the results are non-deterministic from the standpoint of a
>>> client, and this can cause problems and/or confusion)
>>
>> Last time I checked, ALL matching records are returned as a single
>> Resource Record Set - (and in the case of DNSSEC - covered with a single
>> signature).
>>
>> What the receiver does with it is up to that receiver... as you say -
>> some of the information may be discarded.
> If the invoker is using the classic gethostbyaddr() interface, then 
> it'll only see the RDATA from the "first" PTR RR, where "first" is 
> determined by the local nameserver implementation and/or the local 
> Operating System interface for name resolution.
>>
>>> So, although the standards allow multiple RRs, in practical terms, it
>>> only makes sense for a PTR RRset to contain a *single* RR.
>> I would still disagree. When there is forward<-->reverse checking, one
>> may need the complete answer. I certainly have some processes that do an
>> exhaustive check.
> Certainly if one gets down to the resolver-library level and grovels 
> through all of the RRs in the Answer Section of the response packet, one 
> could certainly care more than the typical reverse-resolving 
> app/subsystem would. And any software that builds up certain heightened 
> expectations is likely to complain if those expectations are not met.
> 
>  - Kevin
>>> On 9/11/2014 3:45 AM, Mark Elkins wrote:
>>>
 On Wed, 2014-09-10 at 18:13 -0400, Kevin Darcy wrote:
> No, what I'm saying is that if
>
> example.com owns an A record 203.0.113.48, and
> www.example.com owns an A record 203.0.113.48, then
>
> where does 48.113.0.203.in-addr.arpa point?
>
> Some people will point it at example.com, some will point it at
> www.example.com. What you get is a mish-mosh. No consistency.
 Although I prefer the use of a CNAME solution (CNAME www.example.com to
 example.com), in the case of separate A (and ) records, one could
 point the reverse to both names. Nothing wrong with a PTR record having
 more than one answer. There is then no inconsistency, just choice. After
 all, pretty much every NS record has at least two Right-Hand-Sides
 (Answers)


> If, on the other hand, www.example.com is a CNAME to example.com, then
> it's crystal clear where the reverse record will point -- example.com.
> There is no ambiguity or option for inconsistency.
>
>   - Kevin
>
> On 9/10/2014 5:48 PM, Eliezer Croitoru wrote:
>> Hey Kevin,
>>
>> This is not an issue at all.
>> A PTR is different then a "A" record and can be used by two reverse
>> domain names and only the owner of the IP addresses space can define
>> them.
>> I am not sure if two PTR records for two domains will be applied to
>> one IP but it is possible for two IP addresses to have the same PTR.
>>
>> Can we even use a CNAME as a PTR???
>>
>> Eliezer
>>
>> On 09/11/2014 12:37 AM, Kevin Darcy wrote:
>>> Also, have you considered the forward/reverse ambiguity that arises when
>>> multiple owner names resolve to the same address? To which of those
>>> names does the PTR point?
>>>
>>>   - Kevin

Well, this is certainly getting far away from an answer to the original
qustion!

Originally our web server was only available as www.adi.com. Later I
noticed that a lot of sites were available without the www. So I decided
to allow our web server to be available as adi.com. But I still consider
www.adi.com to be the real name of the server. And I certainly can not
alias adi.com to www.adi.com!

Tom Schulz
Applied Dynamics Intl.
sch...@adi.com
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Re: A record of domain name must be name server ?

2014-09-11 Thread Mark Andrews

In message <5411bdd6.4010...@chrysler.com>, Kevin Darcy writes:
> (Yes, I'm aware that there was a proposal recently discussed on the 
> DNSOP list for an MX-target convention to denote "no mail service 
> offered here". That would presumably solve the problem I cited in the 
> previous paragraph. But AFAIK that proposal is many years away from 
> widespread adoption, and even if adopted, it puts an extra burden on the 
> DNS admins to populate the "no service" MX record, which, again, is 
> going to produce inconsistent results -- some admins will remember to do 
> it; many won't).

No, it's more like formalising existing practice.  Universal adoption
would be a long time off but there is a large existing base of MTA's
that will do the right thing.

Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org
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Re: Promoting slave to master DNS server with dynamic updates

2014-09-11 Thread Mark Andrews

In message 
, John 
Miller writes:
> 
> Hi Eric,
> 
> Depends on how long you can live without dynamic updates, and how many
> dynamic updates it's acceptable to lose in the event of a master failure.
> Journal files are synced every 15 minutes, so in the event of a master
> failure (in a single-master situation), you've lost at most 15 minutes'
> worth of updates.  Stand up a new master (with config management software,
> doable in a few minutes), and you're good to go.

Journals are consolidated into the master file every 15 minutes.
The journal exists to recover from the master dying unexpectedly.
It is also used as the source of IXFR data. Additionaly notify
messages are scheduled to be sent out after 3 seconds so slaves
should only be a couple of seconds behind and they also write
journals.

With UPDATE, NOTIFY and IXFR a set of DNS servers should only loose
up to a couple of seconds of transactions in the event of a master
dying in such a way that the disks are unreadable.

> But why have just a single master?  If you're worried about the primary
> going down, just have a warm standby ready to go.  To keep zone data in
> sync, you could use shared storage, a replicated database (BIND does
> support a database backend), or perhaps some sort of also-notify
> configuration.  To do the failover itself, you could use something like
> Pacemaker/Corosync, ucarp, or similar.  Just pass a VIP back/forth between
> the two -- your NS records would only use the VIP.
> 
> The big issue I see with converting a slave to a master is that you'd have
> to change all of your zone definitions, change your named.conf, and do so
> under time pressure.  Then, when the master came back online, you'd have to
> change your zone definitions again.  With config management software, not
> that hard to do, but servers are cheap these days -- easier just to create
> a failover pair (or group) for your master, then stand up as many slaves
> (doing update forwarding) as you need.  If you purchase a DNS appliance
> (Infoblox, SolidServer, Bluecat, etc.), this is how they handle things.
> 
> Separate issue: you might think about trying out RHEL 6 -- it's using a
> much newer version of BIND which has some updated tools (particularly rndc
> freeze/thaw, HTTP stats interface).
> 
> John
> 
> On Thu, Sep 11, 2014 at 4:48 AM,  >
> wrote:
> 
> > Hello DNS gurus,
> >
> >
> >
> > New on the list, I=E2=80=99ve been tasked by my manager to revamp our dns
> > infrastructure.  I think this list is the best place to get answers.
> >
> >
> >
> > Bind 9.3.6-16 running on RHEL5.7
> >
> >
> >
> > Right now everything run=E2=80=99s on manually editing zone files but we =
> have
> > recently integrated vmware orchestrator (automatic deployment of linux
> > vm=E2=80=99s) in the mix and that complicates things for automated proces=
> ses.  Add
> > Autosys to this and you have one big messy DNS infrastructure and of cour=
> se
> > no team wants to change their work flows (classic).
> >
> >
> >
> > So I=E2=80=99ve written a basic script that would allow everyone (admin=
> =E2=80=99s, vmware,
> > autosys) to use dynamic updates with nsupdate for all tasks.  Everything
> > works dandy but a simple question remains:
> >
> >
> >
> > If the primary goes down for whatever reason, how can we quickly continue
> > to update our DNS records on the secondary?  What are the options?
> >
> >
> >
> > -  Classic slave/master change manually editing the named.conf?
> > What happens to everything in the jnl file on the master if it crashes
> > before the dump and zone transfer?  Lost?
> >
> > -  Nsupdate special ninja trick?  Read something about updating
> > the SOA through dynamic update but didn=E2=80=99t fully understand that p=
> rocess.
> >
> > -  Pray that we get the primary up?
> >
> >
> >
> > The last option would normally be the logical choice but like I said our
> > DNS infrastructure is a mess and those autosys process control DNS record=
> s
> > for their =E2=80=9Cfailover=E2=80=9D feature (yeah I know) so we need a
> > super-lightning-fast switch if we do not want production to stop.
> >
> >
> >
> > Of course the best solution would be something automatic but I haven=E2=
> =80=99t
> > seen anything anywhere.  If it=E2=80=99s manual so be it maybe I would be=
>  able to
> > write a script that could be used by support and minimize human errors.
> >
> > I=E2=80=99m already at least pushing for a more recent bind version and o=
> f course
> > if a special feature exist (maybe I=E2=80=99ve missed it) that provides a=
> n easier
> > solution that would be a super argument to push for something with more
> > features.
> >
> >
> >
> > Thanks in advance.
> >
> >
> >
> > Eric
> >
> >
> >
> > **
> > Ce courrier =C3=A9lectronique, y compris les pi=C3=A8ces jointes, est =C3=
> =A0 l'attention
> > exclusive des destinataires d=C3=A9sign=C3=A9s et rev=C3=AAt un caract=C3=
> =A8re confident

RE: Promoting slave to master DNS server with dynamic updates

2014-09-11 Thread Stuart Browne


> -Original Message-
> From: bind-users-boun...@lists.isc.org [mailto:bind-users-
> boun...@lists.isc.org] On Behalf Of Mark Andrews
> Sent: Friday, 12 September 2014 8:58 AM
> To: John Miller
> Cc: Bind Users Mailing List
> Subject: Re: Promoting slave to master DNS server with dynamic updates
> 
> Journals are consolidated into the master file every 15 minutes.
> The journal exists to recover from the master dying unexpectedly.
> It is also used as the source of IXFR data. Additionaly notify
> messages are scheduled to be sent out after 3 seconds so slaves
> should only be a couple of seconds behind and they also write
> journals.
> 
> With UPDATE, NOTIFY and IXFR a set of DNS servers should only loose
> up to a couple of seconds of transactions in the event of a master
> dying in such a way that the disks are unreadable.

Also worth noting that there is a configuration item that can change the notify 
delay down from 3 seconds if it is so desired.  If you have a low volume of 
updates, you may be able to get away with making it '0', but if you have any 
volume, you really want it to be a few seconds.

Stuart
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BIND 9.10.1rc2 won't build on FreeBSD 10-STABLE

2014-09-11 Thread John Marshall
I can't build BIND 9.10.1rc2 on recent FreeBSD 10-STABLE.
I have tried on both i386 and amd64 variants of the operating system.
BIND 9.10.1rc1 builds fine, as did the beta releases.

Failure looks like this:

  making all in /build/bind/bind-9.10.1rc2/bin/python
  make[3]: don't know how to make dnssec-checkds. Stop

  make[3]: stopped in /build/bind/bind-9.10.1rc2/bin/python
  *** Error code 1

  Stop.
  make[2]: stopped in /build/bind/bind-9.10.1rc2/bin
  *** Error code 1

  Stop.
  make[1]: stopped in /build/bind/bind-9.10.1rc2
  *** Error code 1

Tested on:

  FreeBSD 10.1-PRERELEASE #0 r271181: Sat Sep  6 14:12:21 AEST 2014 i386
  FreeBSD 10.1-PRERELEASE #0 r271289: Tue Sep  9 15:20:15 AEST 2014 amd64

  Note: BIND 9.10.1rc1 builds happily on the above.
  Note: BIND 9.10.1rc2 builds happily on FreeBSD 9.3-RELEASE amd64

Perhaps rc2 introduced something that upsets bmake (the make(1) used in
FreeBSD 10)?

-- 
John Marshall


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Re: BIND 9.10.1rc2 won't build on FreeBSD 10-STABLE

2014-09-11 Thread Evan Hunt
On Fri, Sep 12, 2014 at 09:11:08AM +1000, John Marshall wrote:
> I can't build BIND 9.10.1rc2 on recent FreeBSD 10-STABLE.
> I have tried on both i386 and amd64 variants of the operating system.
> BIND 9.10.1rc1 builds fine, as did the beta releases.

Based on the failure being in bin/python, I suppose it was this:

3946.   [cleanup]   Improved "configure" search for a python interpreter.
[RT #36992]

I'm guessing your system doesn't have a python interpreter, but configure
got confused into thinking it does.  If I'm right, then installing python
ought to make the build work, for the time being.  We'll address the
problem before final release.

Do you still have your config.log?  May I see it?

-- 
Evan Hunt -- e...@isc.org
Internet Systems Consortium, Inc.
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