I have a W2K (SP2) dual home machine as a single server on a small LAN. This machine is also an Xchg2k (SP2) + Web server with one static public IP and one assigned, registered domain name (e.g. domain.com). Since I have to provide I-net access to users, I'm using ISA server for web sharing and caching. I'm trying to configure an externally accessible IM server but have several questions on which I was unable to find answers anywhere. 1. Since it is supposed to be a routed environment, ISA make me change the Default web site (DWS) port from 80 to 81 etc. MS TechNet says that IM works only with port 80. ?? 2. It, also, says that a dedicated web site (s) may be created for use with IM server (s). How this can be done and how can I create several IM virtual severs, if, again, IM use only port 80 and every other Web server would require a different port? When creating an IM virtual server (in the Exchange System Manager), I have to change, temporarily, the port value from 81 back to 80, in the IIS' DWS. Otherwise I'm getting a message that there is "no web site available". 3. TechNet says that when creating an IM virtual server, a FQDN should be entered as the DNS name. IM virtual server wizard finds a host name only, while I understand that a FQDN is supposed to look like: "host.NetBIOSdom.domain.com." The exchange.org, also, suggests to use "im.domain.com" and to create a DNS record for it. Where is the issue? 4. Some sources say that "im.domain.com" has to be created for IM routers only. Should I create it in the environment I have? If, yes. has it to be registered with ISP's NSs or not? 5. DNS. Should I assign, on my internal DNS, an external or internal IP for the IM "A" record? Should I change port # for the _rvp service location record, since the DWS port is changed to 81? Should I create "ïm.domain.com" zone or not, in my environment? etc, etc. I would appreciate your advice on the most suitable configuration. Thanks.