[CentOS] Slow login to system without internet connection

m.roth at 5-cent.us m.roth at 5-cent.us
Tue Nov 20 20:47:40 UTC 2012


Ljubomir Ljubojevic wrote:
> On 11/20/2012 09:25 PM, Les Mikesell wrote:
>> On Tue, Nov 20, 2012 at 12:48 PM, Ljubomir Ljubojevic <office at plnet.rs>
>> wrote:
<snip>
>>> But when I tried to login to my server, it was not instantenous, and I
>>> think it was 15+, maybe even 30+ seconds (I forgot to time it) from
>>> start of ssh command to password prompt. It is in-house connection, so
>>> there is nothing to traceroute.
>>
>> Most server apps will do a reverse-DNS lookup, if only to log the name
>> for the connection, some will try an ident query for the user at the
>> other end of the socket.   A 30+ second delay is a pretty sure sign
>> that one or more of the DNS servers in your resolv.conf did not
>> respond.  Running a local nameserver with a dummy local domain is one
>> way to fix it, but just putting all your local systems in the
>> /etc/hosts file will work too.
<snip>
> So the question is: "is there a setting that will reduce that DNS
> timeout for all running services, maybe like a ping-watchdog that would
> recognize the problem and skip the reverse-DNS lookup if DNS servers are
> not reachable?"
<snip>
What does it say in /etc/nsswitch: is it dns files, or files dns?

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