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Windows Server 2012 r2 DHCP not serving addresses


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#1 sortilego

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Posted 15 May 2016 - 05:29 AM

Hello Bleeping Computer!
 
Yesterday I encoutered a DHCP problem. After windows update and restart, my dhcp won't serve any new IP addresses. The ones wich has been sent before are working but no new IP-s. I tried restarting the DHCP server the Full server sevral times but no success. The settings hasn't been changed, but I checked and it has a lot's of free IP -s and the scope is activated and the server is Authorized to serve DHCP.
I tried adding a RogueDetection disabling registry key but no success.
I tried to check it with wire shark but suprisingly from the server there is no outgoing DHCP packet. I checked from the client too and it send discovery packets but it didn't get any offer.
 
And now I'm out of ideas... :/
 
I will attach the DHCP server log and the client and server Wireshark log.
 
Please if someone has any other ideas or solutions, I would be very happy.
 
Thanks Forward.
 
Thomas

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#2 sflatechguy

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Posted 15 May 2016 - 10:15 AM

Have you tried stopping and restarting the DHCP service on the server?

 

Open the DHCP mmc and right click the server, and select Reconcile all scopes.

Check the bindings on the DHCP server and make sure DHCP is bound to the correct networks.

Check the lease durations to make sure they aren't too short, or too long



#3 Wand3r3r

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Posted 15 May 2016 - 01:16 PM

"The log was temporarily paused due to low disk space"

 

That log entry didn't scream trouble to you???

 

lack of disk space is the best way of permanently lose your server with no recovery except to wipe and restore from backup. Lack of disk space causes problems with the paging file, promotes severe fragmentation and generally causes windows to slowly die.

 

Might want to run chkdsk /f at a command prompt, then run disk cleanup and then defrag the drive for starts.

 

"A lease request could not be satisfied because the scope's address pool was exhausted"

 

Log is telling you there are no available ip addresses. 

 

"I checked and it has a lot's of free IP -s"

Not what the system is telling you.  I would suggest a review or post screen shots of what you are seeing that tells you you have available ips.


Edited by Wand3r3r, 15 May 2016 - 01:19 PM.


#4 sortilego

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Posted 15 May 2016 - 02:09 PM

The sunday log is the newest log. 

There can't be disk space problem, and as you see there is enough lease in the statistics.

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#5 Wand3r3r

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Posted 15 May 2016 - 02:35 PM

Did this server crash or recovered from virus/malware?

This the only DC?

how much ram does this server have?

 

I take it .254 is your gateway?

Which drive houses system files? C:?

MS dns server at 192.168.0.1?  Any errors in the dns log?

DHCP configured to update dns?  There appear to be issues with dhcp communicating with dns according to the logs.

 

lets see a ipconfig /all from the server and a workstation with a working lease

 

You have an interesting mess.  I would still run chkdsk /f on each drive to check for file/disk issues.



#6 sortilego

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Posted 15 May 2016 - 02:47 PM

There wan't any crash or virus.

This is the Only DC and DHCP too.

8GB RAM

 

From the client 192.168.0.1 is the GW to the server because it is the router too. (low budget solution... :/ )

From the server the GW is the NIC other port which gets the internet.

 

C:\ has the file system and it is mirrored

Yes 192.168.0.1 is the DNS too and there is No error in the log

Yes it is configured to update dns, I tried with switching off but didn't help.

 

 

For me it is a nightmare :D

 

 


the left is the server the right is the client


 

 

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#7 Wand3r3r

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Posted 15 May 2016 - 04:27 PM

on the server the primary dns entry should be itself at 192.168.0.1 not google.  I have to assume you have configured the forwarders in dns pointing to your isps dns server and google as secondary.

 

way ms dns works is it looks to itself for name resolution.  this is how your local hosts find the server and each other.  internet dns servers don't have this info.  the local dns server if it encounters a request it cant resolve like google it send the request to the dns servers listed in the forwarding.

 

lease time and dns on the workstation is correct and looks good.

 

178.48.5.85 should not be listed in dhcp since it is the wan ip and not something dhcp can admin.

 

I am thinking sflatechguy is right and somehow dhcp got bound to the wrong interface of 178.48.5.85 not 192.168.0.1 recently

This would explain why there are no dhcp requests.  There would be none on that interface.


Edited by Wand3r3r, 15 May 2016 - 04:28 PM.


#8 sortilego

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Posted 16 May 2016 - 10:12 AM

Now i reinstalled DHCP and RRAS but still bad and not serving addresses...

 

I authorized the dhcp and set to use 192.168.0.1

 

Firewall is off.

 

Any idea, why isnt my DHCP Won'T give IP-s ?:/



#9 Wand3r3r

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Posted 16 May 2016 - 10:21 AM

Post screen shots of the dhcp server screens like before and the most recent log for review






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