Hi,
I have an issue with domain forwarding.
I'm managing public DNS servers for, say, mydomain.com.
We're currently setting a storage system which relies on DNS for load
balancing. The system is made of 4 nodes with IP addresses 10.0.0.1, 2, 3, 4.
The vendor recommands a stub zone to be created with forwarders set to the 4 IP
addresses (i.e their storage system acts as a mini-DNS server).
However, we need this resolution to occur over the internet, so obviously the
stub zone solution does not work because DNS resolvers on the internet would
retrieve the NS list for the subdomain and try to query it directly.
We need to be able to resolve on the internet anything of the format :
xxxx.storage.mydomain.com or yyyy.xxxx.storage.mydomain.com
so what I need is my public DNS servers to be owners of the
storage.mydomain.com but still rely on the storage system for more specific
host resolution.
Some kind of a stealth DNS server but with a forward rather than a master-slave
scheme.
We've tried several solutions but none was fully successful.
SOLUTION 1:
============
in mydomain.com zone file :
storage IN NS ns-storage.mydomain.com.
ns-storage IN A 2.2.2.2
where 2.2.2.2 is a public VIP on the internet that load balances DNS traffic to
10.0.0.1 -> 4
SOLUTION 1 results :
====================
partially works :
when querying google's resolving DNS server for test, both
xxxx.storage.mydomain.com or yyyy.xxxx.storage.mydomain.com resolve fine to the
4 private IP addresses.
however, in certain environments, xxxx.storage.mydomain.com works but not
yyyy.xxxx.storage.mydomain.com.
My guess is that google for some reason sent a recursive query for
yyyy.xxxx.storage.mydomain.com to the NS of storage.mydomain.com while the
other environment was sending an iterative query and thus tried to query the
internal addresses of the storage box.
In the situation that fails what I think is happening is :
Resolver -> mydomain.com NS servers : query NS storage.mydomain.com
mydomain.com NS servers -> resolver : storage.mydomain.com's NS is ns-storage
which translates to 2.2.2.2
Resolver -> 2.2.2.2 : query NS for xxxx.storage.mydomain.com
2.2.2.2 -> resolver : returns 4 NS records corresponding to 10.0.0.1 ->4
Resolver -> 10.0.0.1,2,3 or 4 : fails because private IP is not reachable.
SOLUTION 2:
============
in named.conf :
zone "storage.mydomain.com" {
type forward;
forwarders { 2.2.2.2; };
//forward only;
};
I've tried with and without the "forward only directive" - no change.
Tried it with the internal IP addresses 10.x.x.x and external VIP 2.2.2.2.
SOLUTION 2 results :
====================
fails
a dig for xxxx.storage.mydomain.com gives no answer. Only the authority
section pointing to ns1.mydomain.com & ns2.
SOLUTION 3 :
============
in named.conf :
zone "storage.mydomain.com" {
type forward;
forwarders { 2.2.2.2; };
//forward only;
};
in zone file for mydomain.com
storage IN NS ns1.mydomain.com
storage IN NS ns2.mydomain.com
SOLUTION 3 results :
====================
Direct recursive query to mydomain.com name servers works fine
Requests through another resolver do not work.
dig xxx.storage.mydomain.com +trace gives :
mydomain.com. 172800 IN NS ns1.mydomain.com.
mydomain.com. 172800 IN NS ns2.mydomain.com.
;; Received 117 bytes from 192.42.93.30#53(192.42.93.30) in 102 ms
storage.mydomain.com. 300 IN NS
ns1.mydomain.com
storage.mydomain.com. 300 IN NS
ns2.mydomain.com
mydomain.com. 300 IN SOA ns1.mydomain.com. xxxxxxxx
2013011801 3600 900 604800 10800
I sometimes get loops with the following messages :
storage.mydomain.com. 300 IN NS
ns1.mydomain.com
storage.mydomain.com. 300 IN NS
ns2.mydomain.com
;; BAD (HORIZONTAL) REFERRAL
;; Received 117 bytes from xx in 6 ms
Any advice on how to get this done ?
Thanks in advance !
Thomas
___________________________________________
Thomas Garsiot
Architecture Réseau/Network Architecture, GISSC, CGI Inc.
* (514) 415-3000 #1015293 (SVP ne pas laisser de messages vocaux/ please do not
use voice mail)
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