[CentOS] Caching nameserver -- Name Services Cache Daemon (nscd)

Les Mikesell lesmikesell at gmail.com
Wed Aug 10 17:17:55 UTC 2005


On Wed, 2005-08-10 at 11:56, William Warren wrote:
> well here is what it got this time:
> DNS request timed out.
>      timeout was 2 seconds.
> *** Can't find server name for address 192.168.0.200: Timed out
> *** Default servers are not available
> Server:  UnKnown
> Address:  192.168.0.200
> 
> Non-authoritative answer:
> Name:    cgalliance.org
> Address:  64.202.166.214

This is still nslookup - the timeout/error should not happen
in normal dns resolution.

> How can i fix the revrese resolving issue?

Number to name resolution is exactly the same as name to
number, except that the actual names involved are constructed by
reversing the IP number octets and appending in-addr.arpa.
If your server isn't configured to answer for your private
address ranges itself, it will pass the query off to the
root servers like everything else, and of course no one
else is going to know anything about your private ranges.

If you look at the entry for zone 0.0.127.in-addr.arpa
noting that the filename must be different for each zone
and lives in the directory mentioned at the top (relative
to the chroot location if your version does a chroot),
you will see what you need to do.  If you have webmin,
it will offer to build the reverse zones for machines you
put in forward lookup zones but you can do it by hand or
find a script that does it if you prefer.  To fix your
nslookup issue you only have to make 192.168.0.200 work,
so try adding that to understand the principle.

Also, you mentioned earlier that you wanted to use another
server as the forwarder.  Does that one already have entries
for your private IP's?

I've always wondered why distributions don't come preconfigured
with canned answers for all the RFC 1918 private address space
to reduce the nonsense queries to the root servers.

-- 
  Les Mikesell
    lesmikesell at gmail.com





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