I will be migrating my Windows 2008 Domain from a /24 to a /16 network (as an example only, not intended to be too specific), and the process appears to be poorly documented from my searching. I understand that I will need to change any static IP addressing and modify DNS (reverse lookup zones), DHCP (ranges) and Active Directory Sites and Services (site IP range) accordingly, however I am concerned that there could be some gotchas that I'm not aware of.
Links to any resources or any advice on migrating Windows Domains to new networks would be much appreciated. I will also be more than happy to post my own experiences when the migration has been completed to help future visitors.
That's an awfully big broadcast domain. Why don't you get an L3 switch and make multiple /24s and route between them. That will cut down on broadcast traffic while making it so that you don't have to change anything on the existing servers.
Edit: Upon further review, I haven't really answered the question. While it's not a good idea to do this in your particular situation, the same idea might be valuable for someone expanding a large server subnet from /24 to /23 or something like that.
You should be fine doing this. Configure it on your router/L3 switch first, then your DCs, then the DHCP scopes and AD Site definitions, then modify or create an appropriate reverse lookup zone, then your member servers. You don't need to change anything other than the network settings on each computer/server.