No Mark, This is not a question I am asked to answer for some course We have an implementation where, once the DNS Servers are down, The Client (Our device) Blacklists the IP address of DNS Servers for some period of Time It can only whitelist the server when it receives periodic Responses to a NAPTR Request.
What I did find was even though Our Client was able to send periodic NAPTR requests, we are unable to check what kind of NAPTR requests are sent out Hence my question, What Kind of messages are required by the client to be sent towards server to determine if the DNS IP is reachable or not? Thanks Harshith > From: bind-users-requ...@lists.isc.org > Subject: bind-users Digest, Vol 2230, Issue 1 > To: bind-users@lists.isc.org > Date: Tue, 20 Oct 2015 12:00:01 +0000 > > Send bind-users mailing list submissions to > bind-users@lists.isc.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.isc.org/mailman/listinfo/bind-users > or, via email, send a message with subject or body 'help' to > bind-users-requ...@lists.isc.org > > You can reach the person managing the list at > bind-users-ow...@lists.isc.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of bind-users digest..." > > > Today's Topics: > > 1. How does a Client Verify if the DNS server is Alive or down > (Harshith Mulky) > 2. Re: How does a Client Verify if the DNS server is Alive or > down (Matus UHLAR - fantomas) > 3. Re: How does a Client Verify if the DNS server is Alive or > down (Wah Peng) > 4. Re: How does a Client Verify if the DNS server is Alive or > down (Mark Andrews) > 5. Re: How does a Client Verify if the DNS server is Alive or > down (Phil Mayers) > 6. Re: How does a Client Verify if the DNS server is Alive or > down (Steven Carr) > 7. Re: How does a Client Verify if the DNS server is Alive or > down (Reindl Harald) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Tue, 20 Oct 2015 11:56:54 +0530 > From: Harshith Mulky <harshith.mu...@outlook.com> > To: "bind-users@lists.isc.org" <bind-users@lists.isc.org> > Subject: How does a Client Verify if the DNS server is Alive or down > Message-ID: <blu184-w39a0f214a762089bf7b23b81...@phx.gbl> > Content-Type: text/plain; charset="iso-8859-1" > > Hi All, > > How can a Client verify if the DNS Server is Running(named service is > Running) or Down? > Does it periodically send any messages to the server. What Kind of messages > are required by the client to be sent towards server to determine if the DNS > IP is reachable or not? > > Thanks > Harshith > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <https://lists.isc.org/pipermail/bind-users/attachments/20151020/52fc32d4/attachment-0001.html> > > ------------------------------ > > Message: 2 > Date: Tue, 20 Oct 2015 08:42:04 +0200 > From: Matus UHLAR - fantomas <uh...@fantomas.sk> > To: bind-users@lists.isc.org > Subject: Re: How does a Client Verify if the DNS server is Alive or > down > Message-ID: <20151020064204.ga13...@fantomas.sk> > Content-Type: text/plain; charset=us-ascii; format=flowed > > On 20.10.15 11:56, Harshith Mulky wrote: > >How can a Client verify if the DNS Server is Running(named service is > >Running) or Down? > > Why should client know such info? > The clients needs to have the answer - it sends message and if the server > replies properly, it's up and running. > > >Does it periodically send any messages to the server. What Kind of messages > > are required by the client to be sent towards server to determine if the > > DNS IP is reachable or not? > > what is your problem? > > -- > Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/ > Warning: I wish NOT to receive e-mail advertising to this address. > Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. > Remember half the people you know are below average. > > > ------------------------------ > > Message: 3 > Date: Tue, 20 Oct 2015 14:50:00 +0800 > From: Wah Peng <wah_p...@yahoo.com.sg> > To: bind-users@lists.isc.org > Subject: Re: How does a Client Verify if the DNS server is Alive or > down > Message-ID: <5625e418.9050...@yahoo.com.sg> > Content-Type: text/plain; charset=UTF-8; format=flowed > > Hello, > > Network issue should be detected by other ways. > But DNS health check can be done by sending a normal DNS query to the > server and try get a valid response. > > This is the script what I use to check the health of my DNS server. :D > > #!/usr/bin/perl > use strict; > use Net::DNS; > use POSIX 'strftime'; > use MIME::Lite; > use MIME::Words qw(encode_mimewords); > > my $debug = 0; > my $test_rr = 'alive.example.net'; > my $test_val = '8.8.8.8'; > my @nameservers = qw(1.1.1.1 2.2.2.2); > > for my $ns (@nameservers) { > test_query($ns); > } > > sub test_query { > my $ns = shift; > my $res = Net::DNS::Resolver->new(nameservers => [$ns]); > $res->tcp_timeout(10); > $res->udp_timeout(10); > my $answer = $res->query($test_rr); > > if (defined $answer) { > my @rr = $answer->answer; > if ($rr[0]->address ne $test_val) { > sendmail( "DNS not matched: $ns" ); > print "$ns wrong\n"; > } > if ($debug) { > print "$ns expected value for $test_rr: $test_val\n"; > print "$ns got value for $test_rr: ", $rr[0]->address,"\n"; > } > } else { > sendmail( "Can't query to: $ns" ); > print "$ns wrong\n"; > } > } > > > sub sendmail { > # your email function to send the alerts > } > > Regards. > > > On 2015/10/20 ??? 14:26, Harshith Mulky wrote: > > How can a Client verify if the DNS Server is Running(named service is > > Running) or Down? > > Does it periodically send any messages to the server. What Kind of > > messages are required by the client to be sent towards server to > > determine if the DNS IP is reachable or not? > > > ------------------------------ > > Message: 4 > Date: Tue, 20 Oct 2015 17:51:52 +1100 > From: Mark Andrews <ma...@isc.org> > To: bind-us...@isc.org > Subject: Re: How does a Client Verify if the DNS server is Alive or > down > Message-ID: <20151020065152.bfe313acf...@rock.dv.isc.org> > > > In message <20151020064204.ga13...@fantomas.sk>, Matus UHLAR - fantomas > writes: > > On 20.10.15 11:56, Harshith Mulky wrote: > > >How can a Client verify if the DNS Server is Running(named service is > > >Runnin > > g) or Down? > > > > Why should client know such info? > > The clients needs to have the answer - it sends message and if the server > > replies properly, it's up and running. > > > > >Does it periodically send any messages to the server. What Kind of messages > > > are required by the client to be sent towards server to determine if the > > > DNS IP is reachable or not? > > > > what is your problem? > > My bet this a question from some course that Harshith has been > requested to answer. > > Mark > -- > Mark Andrews, ISC > 1 Seymour St., Dundas Valley, NSW 2117, Australia > PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org > > > ------------------------------ > > Message: 5 > Date: Tue, 20 Oct 2015 10:41:53 +0100 > From: Phil Mayers <p.may...@imperial.ac.uk> > To: bind-users@lists.isc.org > Subject: Re: How does a Client Verify if the DNS server is Alive or > down > Message-ID: <56260c61.9070...@imperial.ac.uk> > Content-Type: text/plain; charset=windows-1252; format=flowed > > On 20/10/15 07:26, Harshith Mulky wrote: > > Hi All, > > > > How can a Client verify if the DNS Server is Running(named service is > > Running) or Down? > > By the presence or absence of a reply to a query. > > > Does it periodically send any messages to the server. > > No. It just sends a query when it has one, and waits for a reply; if it > doesn't get one, it tries another DNS server (if it has one) > > > ------------------------------ > > Message: 6 > Date: Tue, 20 Oct 2015 12:26:34 +0100 > From: Steven Carr <sjc...@gmail.com> > To: bind-users <bind-users@lists.isc.org> > Subject: Re: How does a Client Verify if the DNS server is Alive or > down > Message-ID: > <CALMep06qUWmG8JoRLbey_HviXgzdK65O7hJ=1a_mkbvyu_r...@mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > On 20 October 2015 at 10:41, Phil Mayers <p.may...@imperial.ac.uk> wrote: > > On 20/10/15 07:26, Harshith Mulky wrote: > >> > >> Hi All, > >> > >> How can a Client verify if the DNS Server is Running(named service is > >> Running) or Down? > > > > > > By the presence or absence of a reply to a query. > > That doesn't always verify if the server is running or not, your > client might not be allowed to query it, in which case you may get a > refused response, or it may just not respond to you at all. > > Steve > > > ------------------------------ > > Message: 7 > Date: Tue, 20 Oct 2015 13:31:16 +0200 > From: Reindl Harald <h.rei...@thelounge.net> > To: bind-users@lists.isc.org > Subject: Re: How does a Client Verify if the DNS server is Alive or > down > Message-ID: <56262604.3050...@thelounge.net> > Content-Type: text/plain; charset="windows-1252"; Format="flowed" > > > Am 20.10.2015 um 13:26 schrieb Steven Carr: > > On 20 October 2015 at 10:41, Phil Mayers <p.may...@imperial.ac.uk> wrote: > >> On 20/10/15 07:26, Harshith Mulky wrote: > >>> > >>> How can a Client verify if the DNS Server is Running(named service is > >>> Running) or Down? > >> > >> By the presence or absence of a reply to a query. > > > > That doesn't always verify if the server is running or not, your > > client might not be allowed to query it, in which case you may get a > > refused response, or it may just not respond to you at all. > > and the client can distinct NXDOMAIN, REFUSED, no connection at all > > -------------- next part -------------- > A non-text attachment was scrubbed... > Name: signature.asc > Type: application/pgp-signature > Size: 181 bytes > Desc: OpenPGP digital signature > URL: > <https://lists.isc.org/pipermail/bind-users/attachments/20151020/8b603a46/attachment-0001.bin> > > ------------------------------ > > _______________________________________________ > bind-users mailing list > bind-users@lists.isc.org > https://lists.isc.org/mailman/listinfo/bind-users > > End of bind-users Digest, Vol 2230, Issue 1 > *******************************************
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