PCs get IP setting from not exist DHCP server

By alashhar ·
i have replace a server was doing(domain controller, DNS and DHCP) with new server. so all the roles have been replaced to new server and the old server has been killed. but now i have faced a strange problem. some PCs get the old IP settings (old DNS IP address), although the old DHCP server is killed and not exist and they are configured in automatic IP address.

can anybody explain to me, how and from where they get these settings.

many thanks

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All Answers

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Are you sure that these computers only have the one possibility for DHCP?

by OH Smeg Moderator In reply to PCs get IP setting from n ...

Are there any Managed Switches/Routers or similar on this Network and are there any Child Domains?

Probably more importantly what's the Topology of the Network here?


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Or very long leases?

by TobiF In reply to Are you sure that these c ...

Did your old DHCP by chance offer long-time leases of addresses?

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they get the same settings of the old DHCP

by alashhar In reply to Are you sure that these c ...

sometimes some users call me and told me that they could not connect with the exchange email server, and when i check the IP addresses i found that their PC get the same setting of the old DHCP, and when i select repair the IP address, it get the new IP addresses from the new DHCP and the problem solve.

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Long Leases

by Mehul Bhai In reply to they get the same setting ...

That's what "TobiF" meant in his post. Long Leases naturally.

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Long lease

by Enforcer Drive In reply to Long Leases

If it is along lease the ipconfig /release and ipconfig /renew should give you your new ip address.

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it happens again for the same PC

by alashhar In reply to Long lease

it happens again with same PC, though it has been renewed with the new IP settings.

really strange, i can not find logic reason

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by Enforcer Drive In reply to it happens again for the ...

In that case it is not a long lease. ipconfig /all will tell you the DHCP server that is being used.

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by jeremyrem In reply to PCs get IP setting from n ...

are you using any type of group policy?
try going in cmd and typing gpupdate/force a few times, not sure some pc take longer to receive instructions.

aswell as ipconfig/flushdns

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by alashhar In reply to gp?

how GP and DNS cause this problem?

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by jeremyrem In reply to why

you would be surprised what will happen when you change domain servers, not sure why it does it just happens, at the hospital I work at when we make 1 change some of the pcs take right away and then there are those that need our assistance, or they just wont update

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