DNS, DHCP and classes

I look after a network at a nearby school which includes a SuSE 9.3 system providing basic services, including DHCP and DNS. I have a few problems or, more correctly, "irritations" where something I would like to do doesn't seem to work. The system has three NICs with networks 10/24, 192.168/24 and 192.168/20.

I also only have newsgroup access from home, so there may be long delays before I respond to suggestions.

Irritation 1.
DNS reverse lookup has only been partly working on the 192.168/20 network. After a recent "RTFM" session, I realised that if I "combined" the 192.168 networks into a 192.168/16 DNS zone that might overcome the problem. I made the adjustment late on Friday and, using nslookup, had one success - before that, only systems using the first block of 256 addresses worked and they are all "predefined" in the DNS. Is this the correct answer to the problem or is there a better way?

Irritation 2.
DHCP is set up to recognise all three networks and ignore requests from the 10/24 network. The 192.168/24 network uses a pool for "unknown-clients" and the 192.168/20 network excludes the first block and last three blocks of 256 addresses from a similar pool. This allows internet filtering to be applied using the assigned address to change squid/squidguard filters used. The pool is also split into separate ranges, excluding the .0 and .255 addresses, as we found that any windows client given such an address could not connect to the Windows 2003 server.

At the moment, the four "odd" blocks have predefined addresses using host declarations, which also means they have to be predefined in the DNS as DHCP does not pass these on as an update. What I would like to do is use the "class" declarations to assign systems to one of a number of pools within the "odd" blocks based on the client name and remove the need to perform a manual update when a new laptop is assigned to a teacher, for example.

I have added entries in the appropriate places (by copying the examples in the man pages and changing the names to protect the guilty) of the form:

class "laptop" {
match if substring ( option dhcp-client-identifier, 1, 4 ) = "Dell";
match if substring ( option dhcp-client-identifier, 1, 3 ) = "IBM";
match if substring ( option dhcp-client-identifier, 1, 4 ) = "Acer";
}

pool {
allow members of "laptop";
range 192.168.14.1 192.168.14.200;
}

I assume that case is significant, but addresses seem to be allocated from the general pool (which uses "allow unknown-clients"). There are no reported errors and the strings are the same case as entries in the "leases" file, so I assume I have missed something. Suggestions of things to look for would be welcome.

Irritation 3.
There are some network devices that can be managed via the network but do not supply a client id when requesting an address (and some of these do not seem to have a mechanism for defining a name), so these have host declarations and pre-defined DNS entries. As DNS is set to accept updates from selected addresses (127.0.0.1 and the three windows 2003 server systems that sulk if they are excluded), it would seem that there is no other work-around to get DNS entries for these devices. Is this correct?

Thanks in advance.

PeeGee
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knowledge or consent of the computer user. Software should also be
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