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Re: Strange DNS lookup problems ... I think ...
2004-03-08 17:21:06
I read the last e-mail about this, but lost it, but I think I remember
the basic details.
First, I would try setting up some sort of nameservice caching on the
client and server as a work-around. Some flavors of Linux have a
caching-nameserver package that sets up the correct bind files for you,
then you just put
nameserver 127.0.01
at the top of /etc/resolv.conf. tmdns is supposed to be a more
lightweight caching nameserver of some sort, but I haven't had good luck
with it so far.
"nscd" is a more general-purpose nameservice caching mechanism that can
also cache NIS and LDAP data, but I think there may be a kernel piece to
it that you also need compiled into the kernel. SGI IRIX has "nsd"
which is similar to nscd. If you use nscd or nsd, check
/etc/nsswitch.conf for the order that name services will be checked for
hosts. In particular, you may need to delete "nis+" or "nisplus" if you
don't have NIS+ running on your network--It is often in there as one of
the defaults, but can cause the host res process to crap out at that
point if you don't have NIS+ available on your network.
Second, I would check interface statistics on the client, server,
nameserver, and switches and routers if possible. You want to check for
collisions and/or errors, and keep an eye out for duplex mismatch or
auto-negotiation problems related to certain hardware. Watch out for
misbehaving mini-hubs or mini-switches along the way.
I have had problems with interface hotplug on Linux and certain cards
not detecting a link or auto-negotiating correctly, eg. 3c509B. I had
to put
MII_NOT_SUPPORTED=yes
in /etc/sysconfig/network-scripts/ifcfg-ethX where X is the number of
the interface, to explicitly disable hotplug for that adapter.
--jonathan
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