nscd gotcha

[Nils Philippsen]

On Wed, 2004-11-10 at 09:45 -0600, Brian Millett wrote:
> My server at home uses a dyndns server to keep the current ip address
> uptodate.  Well this morning, the lease expired and it got a new ip.  No
> problem there.  But I could not get to my mail any more.  Strange.  I
> checked to see what it was resolving to:
> [bpm]$ dig mail.momillett.org
> 
> ; <<>> DiG 9.2.4 <<>> mail.momillett.org
> ;; global options:  printcmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 47274
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
> 
> ;; QUESTION SECTION:
> ;mail.momillett.org.            IN      A
> 
> ;; ANSWER SECTION:
> mail.momillett.org.     42930   IN      CNAME   momillett.org.
> momillett.org.          46      IN      A       65.65.192.189
> 
> ;; Query time: 1 msec
> ;; SERVER: 192.9.200.136#53(192.9.200.136)
> ;; WHEN: Wed Nov 10 08:23:15 2004
> ;; MSG SIZE  rcvd: 66
> 
> Ok, that is good, but when I tried to connect as a test, it did not resolv
> to the correct ip:
> [bpm]$ telnet mail.momillett.org 80
> Trying 64.123.62.207...
> telnet: connect to address 64.123.62.207: Connection refused
> 
> I was quite stumped until I saw (strace is nice) that a new service: nscd
> was running.   Ok, so I restarted the nscd daemon, and still a problem. 
> Ok, man pages..... Gee it was working as it should.  There was not a
> negative request as the old addr had been reassigned and was alive.  Only
> the name had been reassigned to a different ip.
> 
> So, should nscd be updated when a 'host','dig', or 'nslookup' request is
> done?  I am playing with the /etc/nscd.conf to tune it for my particular
> setup, but I was wondering what triggers a refresh, or update of the
> cached database?

I've just configured a static IP on my machine and the internal name
server and /etc/hosts only reference this one ;-).

> Also, there is not an entry to the bugzilla for nscd.

That's because it is create from the glibc source RPM (there are only
Bugzilla components for the source RPMs):

nils at gibraltar:~> rpm -qi nscd
[...]
Group       : System Environment/Daemons    Source RPM: glibc-2.3.3-74.src.rpm
[...]

Nils
-- 
     Nils Philippsen    /    Red Hat    /    nphilipp at redhat.com
"They that can give up essential liberty to obtain a little temporary
 safety deserve neither liberty nor safety."     -- B. Franklin, 1759
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