/dev/zero

It feels good when you get something working right.
Before Easter break we covered DHCP and DNS in CIS192. I’m already a DNS expert and fairly familiar with DHCP, so it wasn’t all that new to me.
However I’d noticed for some time in my DNS logs here on the home networks that all the WinXP machines would try to submit DNS updates whenever they would boot. I’d heard about dynamic DNS before but never implemented it.
While doing my homework for lab5a (DHCP) I came across the docs for how to set up the DHCP server to talk to the DNS server to do these updates.
Now I’ve turned off the DHCP server built into the router (it’s very basic. Limits you to a pool of 10 IP addresses and has the hostnames hard-coded (dhcppcXX where XX is the last octet of the assigned IP address.) and set up the (much more capable) DHCP server on my Linux server.
Now all my clients are properly updating DNS when they configure their interfaces.
This also made for an interesting study in configuring Linux (Red Hat to do this. XP tries to submit an update by default. Red Hat does not. It just gets the IP address and goes on it’s merry way, not bothering with DNS updates. Took a bit of parsing through the upteen million scripts Linux uses to start up it’s network interfaces to find the right config file (which, surprise! doesn’t exist by default) to put the right string to get it to submit it’s hostname to the DNS server (or more properly, to the DHCP server which then submits it to the DNS server).
Did any of that make sense?
Probably not. And given that I’m admining a network of 7 machines, all on RFC1918 IP space (private, non-routable addresses) it actually doesn’t mean that much.
But it’s useful to know when/if I ever have to admin a large network again. No more having to give people static IP addresses just so they can keep their hostname across boots.