Ping times are fine, but results are SLOOOOOOOOW.

rev138 · l33t Joined: 19 Jun 2003 Posts: 848 Location: Vermont, USA

I'm having a strange issue that doesn't seem to be addressed on any other threads.

I'm running a gentoo workstation which gets its DNS resolution from a Win2k server. All net traffic responds speedily (ssh, ftp, www, etc), except for ping/traceroute.

If I ping a hostname on the network (I can't ping external addresses, it's a closed network), it resolves the IP almost instantly, but then it takes up to 30-40 seconds for each ping result to display. The ping times retuned are generally < 0.5ms, which is fine... but I can almost make a sandwich and eat it in the time it takes to ping a host 10 times! :evil:

Some related(?) notes:

* If the hostnames are defined in /etc/hosts there is NO slowdown at all.

* I have a laptop running gentoo on this network with the same exact problem.

* none of the windows (any version) workstations on the network have this trouble.

Here's what my resolv.conf looks like:

ckdake · l33t Joined: 10 Apr 2003 Posts: 889 Location: Atlanta, GA

how fast are DNS lookups manually? ie

rev138 · l33t Joined: 19 Jun 2003 Posts: 848 Location: Vermont, USA

Here's what I get. I haven't tried different sized packets, but I don't see how this would make a difference?

rev138 · l33t Joined: 19 Jun 2003 Posts: 848 Location: Vermont, USA

Here's a ping result for that server (the ping times are several ms each, since they're over a partial T1, not on the LAN)

ckdake · l33t Joined: 10 Apr 2003 Posts: 889 Location: Atlanta, GA

rev138 · l33t Joined: 19 Jun 2003 Posts: 848 Location: Vermont, USA

ckdake · l33t Joined: 10 Apr 2003 Posts: 889 Location: Atlanta, GA

how about traceroute? you said it was acting up as well. I'm assuming it just times out and is giving you * * *s but I never asked. heh. Are all of the machines (including the windows one that is working properly) connected to the same networking hardware?
_________________
http://ckdake.com/

rev138 · l33t Joined: 19 Jun 2003 Posts: 848 Location: Vermont, USA

Traceroute gives me this result, but again, it takes a long, long time between each displayed hop. Also, in the case of this command, it puases for about 10 seconds on "traceroute to" before it finishes the rest of that line ("194.1.5.7 (194.1.5.7), 30 hops max, 40 byte packets").

pheelay · Posted: Wed Feb 04, 2004 5:12 pm Post subject:

I have this exact problem on my home LAN so I'd greatly appreciate a solution too!! I'm using djbdns on a Gentoo server. I've just ignored the problem because it hasn't caused any network performance issues as I'm defining all the machines in /etc/hosts also.

If I ping by IP, everything is perfect.
If I ping a hostname (not defined in /etc/hosts), ip resolution is instant, but there is approx 30 seconds between each response. Ping reports 0% packet loss.

Windows machines on the same network do not have this problem.

With traceroute it stalls on 'traceroute to' for about 5-10 seconds before completing the line and actually never finds the destination.

ckdake · l33t Joined: 10 Apr 2003 Posts: 889 Location: Atlanta, GA

That is really pretty weird.

pheelay, what is in your /etc/resolv.conf?

rev138, are you using djbdns?

mine is

rev138 · l33t Joined: 19 Jun 2003 Posts: 848 Location: Vermont, USA

I'm not running any kind of DNS on my local machine, it's from the Win2k server.

pheelay · Posted: Wed Feb 04, 2004 10:29 pm Post subject:

On the server (running djbdns):

atom · Posted: Sun May 09, 2004 6:09 pm Post subject:

my network recently started doing this. i just made some major changes, but before it worked just fine. i use djbdns on an openbsd box. during the changes i upgraded from openbsd 3.4 to 3.5.

has anyone found a fix for this?

moby · n00b Joined: 17 Dec 2002 Posts: 29

Just a guess. Is your DNS server serving up the reverse zones correctly? This will cause very very odd behavior. A lot of old applications rely on reverse lookup, and when it's not present, will work but work dog slow. See if you can do a reverse lookup.

-moby

atom · Posted: Tue May 11, 2004 1:16 am Post subject:

i discovered dnscache was being very slow on my dns server. so i turned it into a forwarding cache. this seems to have alleviated my problems on all but one of my machines. still curious why this one machine is having issues. maybe its time for a reboot

atom · Posted: Tue Jul 06, 2004 2:06 pm Post subject:

just as a follow up to this, i realized i had not set up reverse addresses in my tinydns configuration. the addition of this alleviated any problems i had.