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DHCP Scope not working Windows Server 2012

Zoldy2000
Zoldy2000 asked
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Last Modified: 2017-04-04
So we had 2 existing DHCP servers as follows and there scopes

Server 1
192.168.1.100 through 174
192.168.5.100 through 174

Server 2
192.168.1.175 through 249
192.168.5.175 through 249

Everything works as expected if one fails the other kicks in and works fine

recently we added anther VLAN and Subnet to our network and created these 2 new scopes which now looks like this

Server 1
192.168.1.100 through 174
192.168.5.100 through 174
192.168.2.100 through 174

Server 2
192.168.1.175 through 249
192.168.5.175 through 249
192.168.2.175 through 249

Now the problem is this new subnet 192.168.2.x DHCP only works from Server 1.    If I disable server 1 to test the other DHCP fails from client devices.

I have recreated the scope,   restarted servers... and reset devices and nothing works

Any ideas suggestions to fix?
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Harold BowlinOwner/Network Architect
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Commented:
Is it possible your network guys forgot a helper-ip in the network devices somewhere? When you create a new subnet, it goes on a new VLAN which will require multiple helpers for a failover DHCP server scenario

For instance on a Cisco device....

int vlan 200
ip helper-address x.x.x.x - primary server
ip helper-address x.x.x.x - secondary server

Author

Commented:
yes that is very possible i manage our switches myself and set them up along time ago. they are allied telesyn switches.   does that get configured on all layer 2 switches or just later 3?
Harold BowlinOwner/Network Architect
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Commented:
Just on the L3 switch for that VLAN. If one is working and the other isn't, you should already have an entry for the working one.

Author

Commented:
okay I will look into this and award points once confirmed.

Author

Commented:
I have looked everywhere for IP helper address on our layer 3 switch.   There is not even a reference to it in the manuals.    Could it be called something else.    We have a AT-9924T ... allied telesis switch.
Owner/Network Architect
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Commented:
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Author

Commented:
I found this..   this is the IP address of the one DHCP server that works.     Could bootp relay be the right thing


BOOTP Relay Destinations
Address            Interface
----------------------------
192.168.101.60     -
----------------------------

BOOTP Counters

  InPackets ................... 86897       OutPackets .................. 64705
  InRejects ....................... 0
  InRequests .................. 65525
  InReplies ................... 21372
-------------------------------------------------------------------------------
Harold BowlinOwner/Network Architect
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Commented:
Looks like it. Add the other server in there and it should work.

Author

Commented:
That is the tricky part cannot find the command to add the other server... working on it.

Author

Commented:
resolved issue

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