Richard wrote regarding 'Re: [SLE] Subnet 169.254.0.0' on Thu, Aug 19 at 08:21:
On Thursday 19 August 2004 07:30 am, Jerry Feldman wrote:
I noticed last night while trying to configure my SuSE 9.1 laptop for MIT, that the routing table had en entry for 169.254.0.0. It is coming from the network scripts, ifup-route. It shouldn't hurt, but I was wondering why this was done, or is it something that someone at SuSE set up. I haven't seen any documentation on this either.
Jerry, if you do a whois 169.254.0.0 you will see it eventually goes to some server called BLACKHOLE. As I understand it, that's what it is. When xp fails to get the proper IP from the DHCP server, it gets one of the 169.254 numbers and nothing works. The strange thing is, as soon as Linux fires up on the same machine I get the correct local IP. I'm sure there is some longwinded answer somewhere but the short one is it's a dummy IP.
Now some guru can step in and tell us the REAL STORY!
169.254.0.0/255.255.0.0 is the netblock used by autoconfigured DHCP machines. If you've ever taken a windows box and turned it on without a DHCP server anywhere, it will autoconfigure itself to use an address from that range. It'll then send out a broadcast to see fi anyone else replies on that address, and pick another from that range if the one it chose was taken. And so on. That way, you could have a hub, some wires, and no knowledge of how to configure a network, but still get a couple of home machines to talk to each other. Most DHCP clients now will use that so they can interoperate nicely. --Danny