On 11/20/2012 09:25 PM, Les Mikesell wrote:
On Tue, Nov 20, 2012 at 12:48 PM, Ljubomir Ljubojevic office@plnet.rs wrote:
Now, when there was power failure (works on the transformer there), I lost my internet connection, but router and wireless routers for the rest of my towers were accessible. SSH logins to any of them is instant.
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.
OK, that is what crossed my mind, but what I was hopping for is some elegant solution that would decrease the timeout. My server already has DNS server running and "nameserver 127.0.0.1" as first in /etc/resolv.conf.
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?"
Adding and maintaining 30+ subnets in /etc/hosts is not really a good solution, and booting the server without reachable DNS server in some cases can be really frustrating, like if I boot Lap-top on the silo when internet connection is down (It was happening to me when I ran RHEL 6 beta I think on each opening of the terminal, but I can not say I have seen this lately).