On Fri, Jun 13, 2008 at 03:08:47PM -0400, David Hubbard wrote:
I remember back in the day of old hardware and operating systems we'd intentionally avoid using .255 IP addresses for anything even when the netmask on our side would have made it fine, so I just thought I'd try it out for kicks today. From two of four ISP's it worked fine, from Verizon FIOS and Road Runner commercial, it didn't. So I guess that old problem still lingers?
David
well... .0 and .255 are still special in -some- contexts. they still form the all-zeros and all-ones broadcast addresses for the defined block... so: 192.168.16.0/23 192.168.16.0/32 is unusable 192.168.16.255/32 is useable 192.168.17.0/32 is useable 192.168.17.255/32 is unuseable. crapy CPE, vendor instruction, poor software all contribute to VLSM being poorly understood and these "gotchas" still around - years - later. my recommendation... place your caching nameservers and webservers on these addresses... if you want to force the issue. :) --bill