DC1, DC2 and DC3 are at site A. DC4 and DFS server (2008 R2) are at Site B. DC4 is Server 2003 and not a Global Catalog. DC1, DC2 and DC3 all are Server 2003, FSMO role holders and a Global Catalog. DC1 is Master DNS (SOA) for the Domain, All DC's are also DNS enabled.
Everything was working fine but suddenly after the monthly patch release the issue started. when we bring the DC4 up the DFS namespace is inaccessible. For workaround I have to keep the DC4 down. Please let me know any suggestions to look at this issue?