Article ID: 272076 - View products that this article applies to.
This article was previously published under Q272076
This article has been archived. It is offered "as is" and will no longer be updated.
A Windows 2000-based server running the Network Address Translation (NAT) service with the DHCP allocator function may log the following system event
where x.x.x.x is the IP address that NAT is attempting to lease out to a client, and X.X.X.X is the IP address of the interface running the DHCP allocator service in NAT.
Event ID: 30001
Description: The DHCP allocator was unable to check whether the IP address x.x.x.x is in use on the network for local IP address X.X.X.X. This error may indicate lack of support for address-resolution on the network, or an error condition on the local machine. The data is the error code.
There is a host on the network which has a duplicate of an IP address in NAT's DHCP pool of addresses.
To resolve this issue, use either of the following methods:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.
Before the DHCP allocator service in NAT gives a client a lease for a particular IP address, it sends an ARP request for the IP (a gratuitous ARP) to see if the address is already in use. If a computer (or network device) responds to this ARP request, the DHCP allocator service logs this warning, and tries to issue the next available IP address in the DHCP scope.