Event ID - 14120

Event Id14120
SourceMicrosoft web Proxy
DescriptionThe ISA Server services cannot create a packet filter 157.54.12.183. This event occurs when there is a conflict between the Local Address Table (LAT) configuration and the Windows 2000 routing table. Check the routing table and the LAT to find the source of the conflict. Data: 0000: 15 00 00 00 ....
Event InformationIf you install Microsoft Internet Security and Acceleration (ISA) Server 2000 in Integrated mode on a computer with only one network interface card the above event may be logged for each Web Proxy request. 
CAUSE :
ISA generates a dynamic packet filter for every outgoing connection object so it can listen to the reply from the requested web server. On a machine with only one interface this will fail as it is not possible to do packet filtering.

Installing ISA Server in Integrated or Firewall mode requires a minimum of two network interface cards (NICs) for the packet filtering and Network Address Translation to work properly. This can either be two NICs or one NIC and one dial-up adapter. If you install ISA server in Integrated mode on a computer with only one network interface, ISA Server may log an event 14120 for each Web Proxy request. 
RESOLUTION :
Installing ISA Server in Integrated or Firewall mode on a computer with only one network interface is not supported. To resolve this problem, uninstall ISA Server and install it in Cache mode or add an additional network interface.

Information From a newsgroup post:
CAUSE:
This behavior occurs because when the ISA Web service listens on the external IP address on behalf of the Web server, and the internal client tries to access that service, Web proxy tries to create a packet filter for that address because the proxy views that the address as external (which it is). The packet filter driver fails to create the filter because the address is not reachable through the external interface; instead, the address is reachable through the loop back interface. The result is the event
RESOLUTION:
Although you can ignore this event, you can also resolve this behavior. To do so, on the DNS server that is being used for internal name resolution, create a host record (A record) for the fully qualified domain name that is used by internal us
Reference LinksMicrosoft Web Proxy Event 14120 for Every Web Request

ISA Server Event 14120 Is Logged and Packet Filter Cannot Be Created



IsaServer.Org discussion about 14120.

Proxy Server Documentation Error in LAT Settings for Caching Internet Objects

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