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IP addresses - DNS/DHCP question

Posted on 2012-08-22
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Last Modified: 2012-09-26
We have a small office with about 50 Windows XP computers and a Windows 2003 Server running Active Directory, DNS, and DHCP.  Occasionally,  I will notice that one of the XP machines has a different IP address compared to what the other computers "think" it should be.  For example, someone was trying to use remote desktop today for one of our lab computers, and when they remote desktop'd to the computer name, it couldn't connect.  It turns out the computer trying to connect to it thought the IP address was 192.168.2.122 but when I check the ipconfig information of the target machine, it was 192.168.2.124.  How do I synchronize all the computers to the server so they all "know" the current IP addresses of all the other machines on the network?  I think that if I do an ipconfig/registerdns on the machine with a different IP address (at least different than what the other client computer think it should be) that will register it's current IP address with the DNS server, right?  But then how do I get all the other computers up to date with the DNS server/real IP address assignments?
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Question by:jbobst
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by:JAN PAKULA
ID: 38322968
1 do you have any dhcp reservations active?
2 your Dns - do you have scavenging on + is it enabled for AD secure dynamic updates?
3 Are you sure that this xp machine doesnt have any locally set ip address on local network card?

JAN MA CCNA
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Assisted Solution

by:Sarang Tinguria
Sarang Tinguria earned 248 total points
ID: 38322978
Go to TCP/IP properties of NIC in DNS Client (XP or win7) -> Click advanced-> Click DNS (Tab)-> Make sure you have checked the "Register this connections addresses in DNS" checkbox
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by:JAN PAKULA
ID: 38322981
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What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

 
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Expert Comment

by:Baleboos
ID: 38323006
And get rid of NetBIOS. You have DNS, right?
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Author Comment

by:jbobst
ID: 38323030
I have a few DHCP reservations, but they are in a block of 20 addresses that are excluded from the DHCP server assignments.

Under the "Serve Aging/Scavenging Properties" I do have Scavenge stale resource records checked.

This computer is set to obtain IP address automatically in the network card properties.

The "Register this connection's addresses in DNS" is checked on the NIC.

Not sure if I have NetBios or not...Where do I check that?  The Windows Server has DNS and DHCP setup on it.

This particular lab computer normally is fine with it's ip address.  It just so happened that today it's address wasn't what other computers thought it was.  I assume that is because the Windows Server hasn't updated all the client machines yet or the computer in question didn't communicate properly with the DNS/DHCP server?  That is my question I suppose...how do I syncronize the workstation ip address with the server to make sure all clients and server are on the same page when it comes to ip addressing?  This seems to happen to various machines ever few months.  It's not frequent, but sometimes we notice a machine's ip address is not what all the other clients think it is.  I know that DHCP assigns addresses (none of my computer have static addresses) and I think that the DNS server is supposed to keep a record, or keep track of computer names and their associated IP addresses.  Isn't there some way to just have all the computer do a sync with the server to make sure everything is in order with the IP addressing/computer naming scheme?
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by:JAN PAKULA
JAN PAKULA earned 504 total points
ID: 38323036
are you sure you dont have rouge dhcp server on the network - might be little wireless access point hidden somewhere or some adsl router set up with dhcp server - that usually is the case
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by:JAN PAKULA
ID: 38323040
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by:jbobst
ID: 38323066
There is definitely no rogue dhcp server.  95%+ of the time, all are machines are fine.

So, I looked in my DNS server and there is no entry at all for this particular lab computer or it's claimed IP address.  In my DHCP server, there is an active lease for this lab computer and it has the proper address.  So maybe the question is, why isn't my DNS server seeing this lap computer?  The DHCP "knows" about it...why doesn't the DNS server?  The DNS doesn't even have a record for the "wrong" ip address (which all the other computers think the lab computer has).
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by:jbobst
ID: 38323072
I should clarify that there is no Host A record in the DNS server for the lab computer.
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Assisted Solution

by:JAN PAKULA
JAN PAKULA earned 504 total points
ID: 38323080
can you delete this dns record from dns sever
create dhcp reservation for this pc
ipconfig/flushdns
ipconfig/release
ipconfig/renew
ipconifg/registerdns

and have a look what ip you get in dns

there also might be a problem in layer 2 - with arp mappings

on given pc do

arp -d *
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by:jbobst
ID: 38323118
"can you delete this dns record from the server"...

That is what I am trying to tell you...there is no DNS record for this computer, only a record in the DHCP server.
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Accepted Solution

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Suliman Abu Kharroub earned 248 total points
ID: 38323183
Does the client machine point to the correct DNS server ? try nslookup hostname

what type dynamic updates do you configure ? secure only? if so, try to rejoin the machine to the domain.. it could be a trust relationship with the domain is broken.

is this problem happen only for this xp client or all DHCP clients ?
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by:jbobst
ID: 38438966
Sorry for the delay in closing this question.  The very next day, the computer and DHCP server were completely insync and everything was fine.  Not sure what happened, or what happens on the server overnight, but everything was fine in the morning.  Thanks for the help.
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