I have a single server 2003 R2 with a domain supporting around 90 pc's / laptops + a reserved lease of 30 to allow for resource servers, printers and wireless access points.(Based in a primary school)
The address range is 172.xx.xx.1 to 172.xx.xx.127 and the subnet mask is 255.255.255.128
There have been many problems with address leasing and it has ended up with my reducing
the lease period to 1 day. Another school has moved to a totally different ip range and their old range followed immediately after our own.
I have managed to obtain extra addresses to increase the range to 172.xx.xx.254, with a change in the subnet mask to 255.255.255.0.
The LEA is changing its firewalls etc to accommodate the new range.
The intent was to update during the late afternoon, but as so often happens things didn't go according to plan!
Whilst the LEA was updating the firewall etc I started on the local domain.
Without much experience in this area, I changed all the devices with a fixed ip address to show
the new subnet.
I have changed the server's own network address subnet mask to the correct
subnet, and looked at the dhcp addressing.
I expired/removed the remaining leases so that new would be issued on the next logon.
I looked at the address range, but could see the subnet was greyed out and could not be changed.
I believe the scope needs to be re-set, DNS server address changed, also the gateway, which should be updated to point to the new address provided by the LEA
Flushing by ipconfig /flushdns and /registerdns should clear old addresses.
Unfortunately time was running out and I had to reset all the subnets to the original .128 before the school was closed for the evening to avoid the risk of system failure in the morning.
Before I start again I'd be better off with a full documented plan of what and where to make changes, hence the request for help.
I've looked at the many comments/advice on changing subnets but could do with some advice on which steps I have missed out or need to follow (as I am sure there are many), and probably just where I need to look in the dhcp/dns settings + Active Directory possibly.
Any help would be much appreciated.