At Tue, 22 Oct 2002 23:22:44 +0100, Dave Williams wrote:

Hi

I've just rebuilt our main FS using Suse 8.1 following a complete hard drive failure (and no we didn't have a full backup).

I've never been sure about the settings to use for host name, domain name, name servers and domain search list. Everything has always worked but we sometimes get poor performance which may be related to DNS queries.

Many years back we called our domain derbymoor (school name) and the server derby. However, since we are now connected to broadband and our local machines can find out about the big wide world I wondered if we should use our official domain of derbymoor.derby.sch.uk.

Should we be running a name server ie nscd or named?

I'd run bind9 (a.k.a. named) if it's available on SuSE, and bind8 otherwise. It should act as a caching server by default, which will speed up your internet access for starters, but you should probably set up local zones to handle the lookups that are giving you performance problems. If you are getting behaviour such as telnet, ssh and ftp logins taking over 30 seconds to come up with a prompt, it is probably because of reverse lookups, where the server is trying to discover the name of your client machine. If you simply set up a reverse lookup zone that is authoritative for those addresses, you can use the 127.0.0.1/8 zone as inspiration, then that will be much quicker. You don't even need to put anything much in the table, since an authoritative "I don't know" will be just as quick as a useful answer from your local server. (check out /etc/bind/named.conf or /etc/named.conf, or perhaps files under /var/named depending on how up to date SuSE is) Things to keep in mind: In the reverse lookup tables, all the addresses are the wrong way round, so 192.168.1.2 becomes 2.1.168.192.in-addr.arpa. Don't forget the dots on the ends of domains that you don't want the default domain tacked onto in the database files. In a reverse lookup table for the zone 1.168.182.in-addr.arpa. This: 2 IN PTR server2.derbymoor.derby.sch.uk. is fine, but this: 2 IN PTR server2.derbymoor.derby.sch.uk is not, because what that actually means is this: 2.1.168.182.in-addr.arpa. IN PTR server2.derbymoor.derby.sch.uk.1.168.182.in-addr.arpa. You could stick with the old domain, although it will probably cause confusion in the long run. Either way, it's probably worth setting up a zone for it, so that you are not doing pointless lookups for pc123.derbymoor on the Internet, and then waiting for the reply. If you set up a local zone for derbymoor.derby.sch.uk, don't forget to include things that are actually external. For example: www.derbymoor.derby.sch.uk. IN A 217.79.109.202 or (for short): www IN A 217.79.109.202 otherwise the rest of the world will still see them, but you won't. Once done, if you still have things that look like DNS timeout delays, switch on tracing (BIND8: "ndc trace", BIND9: "rndc trace"), do the thing that's causing the problem, and then look at the logs (in the default directory specified in named.conf, called named.run). You'll probably either find out the client is misconfigured, or that you need to add another zone to shut it up. I think that's probably it for Phil's nought to DNS in 60 seconds. :-) You probably ought to grab a copy of the latest O'Reilly DNS/BIND book if you're going to do anything even slightly ambitious with DNS. Cheers, Phil. -- Say no to software patents! http://petition.eurolinux.org/ |)| Philip Hands [+44 (0)20 8530 9560] http://www.hands.com/ |-| HANDS.COM Ltd. http://www.uk.debian.org/ |(| 10 Onslow Gardens, South Woodford, London E18 1NE ENGLAND