DNS CNAME record persists after removal

[Saxon Jones]

Our Windows 2000 Advanced Server DNS service is experiencing a very strange
problem. We have a domain, tubtron.com, which had a WWW CNAME record; this
worked apparently up until a few days ago. Now there is nothing I can seem
to do that will make it work. An example nslookup:

C:\Documents and Settings\saxonj>nslookup www.tubtron.com ns1.interbaun.com
Server: dns.interbaun.com
Address: 199.185.130.34

Name: www.tubtron.com

It doesn't come back with any address or anything (I didn't just forget to
copy the last line, that's the whole output). Our secondary server serves
it just fine. The zone files on each DNS server are identical, same version
and all.

The strangest part is that if I remove the zone from our primary server it
still gives the above result. A whois on the domain still shows both of our
servers as the authoritative for that domain. I can't help but think the
server is not authoritative and is just forwarding the request, but it seems
not to be the case.

Any suggestions? Am I missing something that is glaringly obvious?

Thanks.

 

[Kevin D. Goodknecht [MVP]]

In Saxon Jones <[email protected]> posted a question
Then Kevin replied below:
: Our Windows 2000 Advanced Server DNS service is experiencing a very
: strange problem. We have a domain, tubtron.com, which had a WWW
: CNAME record; this worked apparently up until a few days ago. Now
: there is nothing I can seem to do that will make it work. An example
: nslookup:
:
: C:\Documents and Settings\saxonj>nslookup www.tubtron.com
: ns1.interbaun.com Server: dns.interbaun.com
: Address: 199.185.130.34
:
: Name: www.tubtron.com
:
: It doesn't come back with any address or anything (I didn't just
: forget to copy the last line, that's the whole output). Our
: secondary server serves it just fine. The zone files on each DNS
: server are identical, same version and all.
:
: The strangest part is that if I remove the zone from our primary
: server it still gives the above result. A whois on the domain still
: shows both of our servers as the authoritative for that domain. I
: can't help but think the server is not authoritative and is just
: forwarding the request, but it seems not to be the case.
:
: Any suggestions? Am I missing something that is glaringly obvious?
:
: Thanks.

What is the FQDN the CNAME points to?
Is that name on this server?

When you use a CNAME and you do a lookup on the CNAME it does not return an
IP address, it returns a FQDN that must be resolved before it can return an
IP address.
What I am saying is I think the problem might not exactly be the CNAME but
it is the FQDN the CNAME points to. Can you resolve that name to an IP?

 

[Jonathan de Boyne Pollard]

SJ> The zone files on each DNS server are identical, same version
SJ> and all.

No, they aren't. Your content DNS server at 199.185.130.34 has
a "www.tubtron.com." "zone", whereas your content DNS server at
199.185.131.5 does not.

SJ> The strangest part is that if I remove the zone from our
SJ> primary server it still gives the above result.

That's because you removed a "zone" that was irrelevant, the
data for the domain name that you were querying actually being
within a different "zone".

SJ> Am I missing something that is glaringly obvious?

Yes. What "zones" were shown in the DNS Manager when you looked ? (-:

 

[Saxon Jones]

Yes, I can do an nslookup of the target of the CNAME without problem.

But what is more baffling is that if I remove the zone from the name server
(ns1.interbaun.com) so that it no longer has any record of tubtron.com and I
also remove the .dns zone file from C:\WinNT\System32\DNS I can still do an
nslookup on that server and it will still return the exact same response.

Which is why I believe the problem is not with the CNAME record but with
either a cache on the nameserver (I've cleared the cache and I've rebooted
the server to no avail) or it is my name server fetching the result from
another server, though the only authoritative ones are both mine
(ns1.interbaun.com and ns2.interbaun.com).

 

[Kevin D. Goodknecht [MVP]]

In Saxon Jones <[email protected]> posted a question
Then Kevin replied below:
: Yes, I can do an nslookup of the target of the CNAME without problem.
:
: But what is more baffling is that if I remove the zone from the name
: server (ns1.interbaun.com) so that it no longer has any record of
: tubtron.com and I also remove the .dns zone file from
: C:\WinNT\System32\DNS I can still do an nslookup on that server and
: it will still return the exact same response.
:
: Which is why I believe the problem is not with the CNAME record but
: with either a cache on the nameserver (I've cleared the cache and
: I've rebooted the server to no avail) or it is my name server
: fetching the result from another server, though the only
: authoritative ones are both mine (ns1.interbaun.com and
: ns2.interbaun.com).
:
According to my lookup you have three NS records.

tubtron.com

Server: ns1.interbaun.com
Address: 199.185.130.34

DNS request timed out.
timeout was 2 seconds.
tubtron.com internet address = 206.75.252.64
tubtron.com nameserver = ns1.interbaun.com
tubtron.com nameserver = ns2.interbaun.com
tubtron.com nameserver = ralph.interbaun.net<---where is this NS?
tubtron.com
primary name server = ns1.interbaun.com
responsible mail addr = support.interbaun.net
serial = 14
refresh = 900 (15 mins)
retry = 600 (10 mins)
expire = 86400 (1 day)
default TTL = 3600 (1 hour)
tubtron.com MX preference = 10, mail exchanger = mx.interbaun.com
ns1.interbaun.com internet address = 199.185.130.34
ns2.interbaun.com internet address = 199.185.131.5
ralph.interbaun.net internet address = 199.185.130.3
mx.interbaun.com internet address = 199.185.130.38
mx.interbaun.com internet address = 199.185.130.37

What seems to be missing is the blank record does one exist in the two
nameservers you are looking at?