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The ipconfig of my Windows Server 2003 server shows that the IP addresses,, and are assigned to it. However, when I look in the Advanced TCP/IP Settings window for that connection, I only see the IP address of listed there.

In the Support tab for the connection, it shows that it's connected through, and in the Support > Details window, it shows all the previously mentioned IP addresses.

Where are these phantom IP addresses being stored and how can I free them up so I don't have any IP conflicts?

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I failed to mention this but the server was part of a SQL cluster, so and were the cluster group IP addresses. Found it under the Cluster Administrator. – tridium Apr 13 '10 at 16:29

Nic's that are used in Clustering (whether MSCS or MSNLB) MUST have multiple IP's bound to them. These virtual IP's are always listed in the appropriate role's MMC Snap-in (Cluster Admin for MSCS and NLB Manager in MSNLB). All IP's are listed in the Advanced TAB for TCP/IP Settings of any NIC's involved in a cluster:

(right-click the interface-->properties-->(double-click 'Internet Protocol (TCP/IP)')-->advanced-->(look in the IP addresses window)

It's on you to determine what IP's are available before binding them to a clustered node. Keep an Excel spreadsheet with a workbook for each subnet in your LAN...

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You can check the leases of the DHCP server. In windows DHCP servers, it will accept a description field. (Just in case, to get there: Start -> Admin Tools -> DHCP , then expand server -> expand scope -> click Address Leases)

Depending on the function of your server, it might actually be using the separate IPs. RRAS is notorious for this.

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