servfail response message question

[Mark Andrews]

In message <1372206137.34187.YahooMailNeo at web161406.mail.bf1.yahoo.com>, RYAN C
HERVENKA writes:
>
> I currently have a domain example.com authoritative on my Ubuntu server
> and it is delegating gslb.example.com to my load balancer.
>
> www.example.com is a CNAME for www.gslb.example.com
> 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.
>
> 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

Not without more details.

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org