I needed to expand the IP addresses available for our internal use so I was going to add an additional sequential subnet. The current subnet mask is 255.255.255.254.0 I went to network connections on the server, selected the local area connection and changed the netmask to 255.255.252.0 and now I can not access the server by name from some computers.
When I changed the netmask from 255.255.255.254 to 255.255.255.252 it removed it from some of the DNS servers. It finally updated after 45-60 minutes.
I changed it on another 2008 server without any of these issues.
should changing the netmask on a 2008 64bit server cause this issue?
Alter the netmask/scope and import it back.
This way you will maintain any IP reservation you may have as well as IP range exclusion
If you are increasing from a 509 possible usable IPs/host to a 1021 there are many devices where this change Needs to be done including VPN/firewalls if any, managed switches, etc.