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Strange IP Address Happenings

By Anthony Waters ·
I have a network running about 300 Windows XP clients and using a Windows 2003 server for DHCP as well as DNS. Over the past few weeks, about a dozen clients have had problems getting to the network as well as Internet. Some can ping the default gateway, some cannot. If we give them a different IP, all is well. Any ideas on what could be happening?

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by ASteinberg In reply to Strange IP Address Happen ...

Try to check the ip addressing allocation on the affected station. You can go to Network Connections and open the status of your Local Area Connection. Click on the Support tab and then at the Details button. It is equivalent to the ipconfig /all command, but has the GUI and the Repair button right below.

Another way to get diagnostics is to issue the command "netsh diag gui".

With the diagnostics, you'll have information to go to the DHCP server and look for the IP leases.

I see that maybe you have one of two possible problems: IP addressing space exhausted (more concurrent connections than IPs available) or excess collisions on your LAN. The first problem can be corrected directly on DHCP server, the second requires further investigation on you cabling and switches.

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by hozcanhan In reply to Strange IP Address Happen ...

Dear Anthony , you say you have 300 stations . IF you have class c network ( netmask : then you are out of address space = you can have up to 254 total stations on the net at the same time . you are hiting that limit. Try sub netting . use the downloads and tutorials , previously asked similar questions to get rid of the pirfall . Good luck !

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by 3xp3rt In reply to Strange IP Address Happen ...

hozcanhan@... has right. Max allowed computers in one LAN is 254. The solution? You can configure two subnets with different IP like, and the other The two LAN's gateway computers on next level side can use dhcp to windows 2003 server. Good luck

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by jdclyde In reply to Strange IP Address Happen ...

Remember, when you subnet, you REQUIRE a ROUTER for the two LANS to talk.

If using a Cisco, if you have two lan ports use one for each. Of not, you can "subinterface" the port.

Make sure you have a decent switch for the core.

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by Anthony Waters In reply to Strange IP Address Happen ...

Forgot to mention a few key pieces of information. The DHCP scope has a subnet of fiving me 1022 possible IP addresses. When I factor in various exclusions, the total available IP address are approx 880. The client machines do receive IP addresses from the correct DHCP server. We are running all cisco swtiches.

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