Troubleshooting network browsing issues

If you have a multi-subnet network with Active Directory deployed as a single domain with multiple domain controllers, and you find that users on one subnet can no longer see network resources on other subnets, it may be that your domain controller that has the PDC Emulator role is offline. This is because the PDC Emulator always hosts the Domain Master Browser role for NetBIOS browsing using the Browser Service, and if this role is missing then domain controllers on other subnets (which act as Master Browsers for their subnet) will be unable to update their browse lists.

Article written by MyComputerAid.com