Hello, scene: Two identical webservers (front end) using NLB, in DMZ, stand-alone Third webserver in internal network, in domain, used as a master/edit server (all edit/admin operations occur here) problem: Cache notifications from edit server to front end servers failed, despite the setup where the "ping" functionality reported everything to be OK. IIS log showed, that when "pinging", the edit server first made a anonymous request and got 401 response, and immediately did another request using the credentials given in the setup, and got response 200 (OK). For some mystical reason, those credentials are not used/even tried during normal operation. when there happens an edit action in edit server, it sends cacherefresh request to front end servers, gets 401 responses, but never tries to do a authenticated request. Why? I did a workaround by allowing anonymous access to front end webservices folder and restricting it by IP address instead, but authentication should work, shouldn't it? Could it relate to the fact, that front end servers have no (originating) access to internal network?