Is my configuration messed up?

Answered Mon, 1 Apr 2002

> My organization just recently set up its own DNS Servers (BIND 9running on
> Linux). We just started to have some e-mail delivery problems,
> which caused me to investigate.
>
> One of the sites that is having trouble e-mailing us is cannondale.com. I
> looked up their name servers and then did an nslookup for our mail server
> (mail.juniata.edu) on their name servers. It came back as
> mail.juniata.edu.juniata.edu. I know this can happen if the configuration
> files are not correct, but I thought that mine were good. If I do an
> nslookup of the same hostname (mail.juniata.edu) on my name server, it comes
> back correctly (without the extra juniata.edu). This information is also
> incorrect on the root server a.root-servers.net.
>
> Here is the response that I received when doing the nslookup for
> mail.juniata.edu on cannondale.com's name servers (auth62.ns.uu.net):
> > server auth62.ns.uu.net
> Default Server: auth62.ns.uu.net
> Address: 198.6.1.19
>
> > mail.juniata.edu
> Server: auth62.ns.uu.net
> Address: 198.6.1.19
>
> Name: mail.juniata.edu.juniata.edu
> Served by:
> - A.ROOT-SERVERS.NET
>   198.41.0.4
>
> - H.ROOT-SERVERS.NET
>   128.63.2.53
>
> - C.ROOT-SERVERS.NET
>   192.33.4.12
>
> - G.ROOT-SERVERS.NET
>   192.112.36.4
>
> - F.ROOT-SERVERS.NET
>   192.5.5.241
>
> - B.ROOT-SERVERS.NET
>   128.9.0.107
>
> - J.ROOT-SERVERS.NET
>   198.41.0.10
>
> - K.ROOT-SERVERS.NET
>   193.0.14.129
>
> - L.ROOT-SERVERS.NET
>   198.32.64.12
>
> - M.ROOT-SERVERS.NET
>   202.12.27.33
>
> Also we host several other domains. When I do a lookup for those they come
> back with juniata.edu on the end of them as well. Here is an example of one of those:
> > campbluediamond.org
> Server: auth62.ns.uu.net
> Address: 198.6.1.19
>
> Name: campbluediamond.org.juniata.edu
> Served by:
> - A.ROOT-SERVERS.NET
>   198.41.0.4
>
> - H.ROOT-SERVERS.NET
>   128.63.2.53
>
> - C.ROOT-SERVERS.NET
>   192.33.4.12
>
> - G.ROOT-SERVERS.NET
>   192.112.36.4
>
> - F.ROOT-SERVERS.NET
>   192.5.5.241
>
> - B.ROOT-SERVERS.NET
>   128.9.0.107
>
> - J.ROOT-SERVERS.NET
>   198.41.0.10
>
> - K.ROOT-SERVERS.NET
>   193.0.14.129
>
> - L.ROOT-SERVERS.NET
>   198.32.64.12
>
> - M.ROOT-SERVERS.NET
>   202.12.27.33
>
> Please let me know if you have any idea what is happening or if you can
> point me to someone who can help. Some namesevers do provide the correct
> lookups for computers on our domain.

This is happening because of a combination of two things:

- You're using an old version of nslookup, which appends the search
list before looking up a domain name as-is. Your search list includes
juniata.edu (so that people there can type "ping foo" and get to
foo.juniata.edu).

- The name servers you're querying have recursion turned off. When
you send them recursive queries (like nslookup does by default), they
don't bother querying your name servers for the answer; they just
send a referral back. So when nslookup sends them a query for a
domain name like mail.juniata.edu.juniata.edu, the just say, "Go ask
a root name server."

The short answer is that this doesn't indicate any misconfiguration
of your name servers.

By the way, if you want to avoid having nslookup apply the search
list, use a dot at the end of the domain name you're looking up:

> mail.juniata.edu.

cricket