Barry,
The Ubuntu server is delegating a sub-domain to the LB. The LB is authoritative
for the domain and is responding to client requests correctly. I removed the @
IN AAAA ::1 from the db file within the primary domain and the response was
sent back to the client from the ubuntu server. Leaving the ipv6 RR in the zone
db file caused the servfail. I don't know why.
Thanks,
Ryan
________________________________
From: Barry Margolin <bar...@alum.mit.edu>
To: comp-protocols-dns-b...@isc.org
Sent: Wednesday, June 26, 2013 10:24 AM
Subject: Re: servfail response message question
In article <mailman.668.1372206152.20661.bind-us...@lists.isc.org>,
RYAN CHERVENKA <ryan_cherve...@yahoo.com> wrote:
> I currently have a domain example.com authoritative on my Ubuntu server and
> it is delegating gslb.example.com to my load balancer.Ý
www.example.com is a
> CNAME for www.gslb.example.comÝ
Gslb.example.com has an NS record pointing to
> the LB
Client sends query for www.example.com to Ubuntu DNS server. The
> Ubuntu DNS server sends a query to the load balancer for www.gslb.example.com
> and the LB responds to the Ubuntu DNS server with the right A record in the
> answer section. However, the Ubuntu server responds to the client with
> servfail.Ý
When I look at the pcap from the Ubuntu server, the LB is
> responding to it with the correct IP but the dig response from the Ubuntu
> server to the client shows "no servers could be reached" when I dig against
> the Ubuntu. I also see the same message in the dns response in the pcap
> (obviously).
Ryans-MacBook-Pro:~ ryanc$ dig @10.10.1.50 www.example.com <-me
> querying the Ubuntu for www.example.com
; <<>> DiG 9.8.3-P1 <<>> @10.10.1.50
> www.example.com
; (1 server found)
;; global options: +cmd
;; connection
> timed out; no servers could be reached
Do you have any ideas as to why this
> is happening?
Ryan Chervenka
Why is the Ubuntu server sending the query to the LB at all? To emulate
how a caching server works, you should be sending queries WITHOUT the RD
flag, so the Ubuntu server should return a delegation to the LB, and
then the caching server should query the LB.
Regarding the problem as you state it, is the LB responding
authoritatively?
--
Barry Margolin
Arlington, MA
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