Installing security update MS05-019 or Windows Server 2003 Service Pack 1 may cause network connectivity between clients and servers to fail Symptoms Network connectivity between clients and servers may fail. This failure occurs after the installation of either security update MS05-019 or Microsoft Windows Server 2003 Service Pack 1 (SP1). Any one or more of the following symptoms may occur: Inability to connect to terminal servers or to file share access. Failure of domain controller replication across WAN links. Inability of Microsoft Exchange servers to connect to domain controllers. During the PathMTUDiscovery process, several routers on the route to the destination send MTU updates to the source host. One of the possible reasons for this could be that source and destination hosts are in different WAN segments. Additionally, these segments are connected through a tunnel with a small MTU. Network load balancing, dynamic routing, or both are used. In this scenario, there are several possible routes to a destination that has MTUs that are different from the MTU of the sending subnet and that are different from each other. Therefore, changing the route of IP packets over time can produce several MTU updates for the destination address. Note There may be some other similar scenarios where these symptoms occur. These scenarios can typically be diagnosed by sniffing the network traffic on either the source host side or on one of the intermediate network routers. If there are multiple ICMP destination unreachable messages sent over time for a destination, the source host that has the MS05-019 security update or Windows Server 2003 SP1 installed is likely to have this problem. Get the update here.
