Servers cannot see each other's sites (networking)?

Question

I have 3 Servers All Hosting Websites, no domains or anything, all three have static IP addresses

ServerA - Hosted at data center
ServerB - Hosted at same data center consecutive IP addresses
BackupServer - Run from my house

I just replaced ServerA with a new machine.

Before the switch all three servers talked to each other and could see the websites run on any of the servers.

After the switch BackupServer and ServerA cannot see or communicate with each other at all. I.e. BackupServer cannot open the site hosted on ServerA and vice versa.

BackupServer can see ServerB's site and vice versa. ServerB can see ServerA's site and vice versa.

All other machines can see the sites of all three servers so the sites seem to be operating normally.

Can anyone give me any idea of settings, configurations or anything I could possibly look at to explain the lack of connection between ServerA and BackupServer? Any pointers would be very helpful! Thanks much.

All 3 servers are running Windows 2003 Server

Answer 1

With no domains, it's not a "trust" issue. Trust relationships can only be established via domain. It's probably a security issue. Check your account settings. Does the account you're using on Backup Server have permissions to log on remotely to ServerA? Permission to log on through terminal services? Permission to log on locally (doubtful this is the problem). Is ServerA blocking access from BackupServer by IP address or MAC address? It's almost certainly a lack of permissions on the account you're using to try to access A from Backup. Failing that, A is blocking access from Backup.
Since the permissions between A and B are functioning, verify you have the same permissions between A and backup.
(I'm assuming you made no changes to your firewall, and the IP address of A is the same as the old A).

Answer 2

What are you running for an operating system? Maybe a trust problem?