[CentOS] nscd

Mon Mar 25 23:06:31 UTC 2013
Gary Greene <ggreene at minervanetworks.com>

On Tuesday, Cliff Pratt wrote:
> On Tue, Mar 26, 2013 at 6:26 AM,  <m.roth at 5-cent.us> wrote:
>> Has anyone had problems accessing random websites since going up to 6.4?
>>
>> Since about the day after I got partly upgraded, if I try to access
>> nytimes.com, or orbitz.com, I get server not found.
>>
>> With a lot of work, I, my manager, and the other admin, found that setting
>> options edns0 in /etc/resolv.conf fixed it - I suspect that the network
>> folks updated their internal nameservers (which are M$) about that time...
>> but... we got this Thurs. Friday, I went to look, lunchtime, at a story,
>> and back to the same. Later, and I think I was playing around, it came
>> back.
>>
>> Just now, over lunch, it failed... until I restarted nscd. My manager
>> tells me it's caching... but it seems to be caching momentary failures.
>>
>> So: has anyone else seen oddness that might be related to nscd?
>>
>Do you want the whole book? 'nscd' is a synonym for weird. I've had
>many strange DNS issues which have been solved by either bouncing nscd
>or purging its cache entries.
>
> However, you appear to be using nscd on your machine to cache DNS and
> using the internal MS DSN servers to do the actual lookups. Am I
> correct? In which case, the MS DNS server should be caching the DNS
> lookups anyway, so you probably don't derive a lot of benefit from the
> nscd unless you do a lot of repeated DNS lookups.
> 
> Cheers,
> 
> Cliff

NSCD is also necessary if you're running an LDAP or NIS environment, so don't just turn it off if you're using external authentication services. In a Winbind environment, NSCD is unnecessary however.

--
Gary L. Greene, Jr.
Sr. Systems Administrator
IT Operations
Minerva Networks, Inc.