Henrik, See answers: >> Why two VIP and how do clients select which VIP they should connect to? DHCP scopes for each VLAN are configured with the options for the auto-discovery proxy (i.e. 172.16.10.7). They are using NTLM at the moment so hostname is not a problem. Moving to Kerberos though will be... >> WHat is the multicast addresses used for? Comms between the proxies - it's how the VIPs decide their priorities etc. Clients are completely unaware of them. >> I usually do a setup very similar to what you describe by using Linux heartbeat using it's ldirectord component for managing the load balancing. This scales to pretty much any number of hosts using one or more VIP. One thing though is that I'm not wanting to NLB - just have the failover capability if I want it. Does your setup still allow that? Nick ** Please consider the environment before printing this e-mail ** The information contained in this e-mail is of a confidential nature and is intended only for the addressee. If you are not the intended addressee, any disclosure, copying or distribution by you is prohibited and may be unlawful. Disclosure to any party other than the addressee, whether inadvertent or otherwise, is not intended to waive privilege or confidentiality. Internet communications are not secure and therefore Conde Nast does not accept legal responsibility for the contents of this message. Any views or opinions expressed are those of the author. Company Registration details: The Conde Nast Publications Ltd Vogue House Hanover Square London W1S 1JU Registered in London No. 226900