Possible Lookup Problem

ceberly at gmail.com ceberly at gmail.com
Tue Nov 8 17:42:04 UTC 2005

I've had some people come to me with concerns about our dns servers so
I decided to start doing some digging.  Basically, when querying our
servers for lets say the aol.com mx records, after the TTL expires my
server stops showing the ip's of the mx records in the additional
section  of the dig.  When I query other servers for the same
information, they tend to update right away after the TTL expires.
For example, after the 300 seconds expires for all of the mx records,
here is what I get on a dig:

root at gtr2:/etc/namedbfiles/hint# dig aol.com mx

; <<>> DiG 9.3.0 <<>> aol.com mx
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29109
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 4, ADDITIONAL: 0

;aol.com.                       IN      MX

aol.com.                3231    IN      MX      15
aol.com.                3231    IN      MX      15
aol.com.                3231    IN      MX      15
aol.com.                3231    IN      MX      15

aol.com.                3231    IN      NS      dns-01.ns.aol.com.
aol.com.                3231    IN      NS      dns-02.ns.aol.com.
aol.com.                3231    IN      NS      dns-06.ns.aol.com.
aol.com.                3231    IN      NS      dns-07.ns.aol.com.

And continued digs show the same information.  After awhile, maybe 10
minutes, I'll start getting the additional section containing the mx
record ip address again.  But like I said, if I query other servers,
after the TTL expires, the additional section lights back up with at
least 1 of the expired servers.

Is this normal?  If not, what may be causing this problem?

Thanks for any help.  I've never really needed to try to troubleshoot
bind before, so I'm at a loss.


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