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Two DHCP servers (router-managed, Windows-managed) -- want to consolidate to one

Posted on 2006-06-21
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Last Modified: 2013-12-03
Running Windows Server 2003 Enterprise Edition x64 behind a Linksys RV0041 router.

The OS is running a DHCP server for scope 192.168.0.10 - 192.168.0.254 (no static reservations)
The router is running a DHCP server for scope 192.168.1.100 - 192.168.1.199 (no static reservations)

The two systems permanently connected to the router have, in the TCP/IP settings for their LAN connections, static internal IP addresses corresponding to the scope controlled by the router.

My remote XP Pro system, when connected via VPN (also managed by the server OS), is assigned an IP like 192.168.1.206, which is not technically in either of those pools, so I'm not sure what is going on there.

Not only do I think two DHCP servers are unnecessary and possibly conflicting (please correct me if I'm wrong), but our DNS server (managed through the OS) has never consistently responded to remotely (VPN) connected requests for DNS names:  from my remote XP Pro system, when connected to the network via VPN, I can navigate to \\192.168.1.x\share\... but not to \\server\share\...  However, systems physically on the network can refer to servers by their DNS names (in TCP/IP for those network connections, localhost or the IP of the server hosting DNS is specified as the DNS server).

I would like to consolidate the DHCP servers to one and do it the right way, and hopefully resolve this DNS issue in the process.  I hope one or more of you can help me do this the right way so that I don't screw anything up, as the servers are physically located some 200 miles from where I am right now.

Thank you...
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Question by:psk1
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Jay_Jay70 earned 250 total points
ID: 16955877
i agree 100%, two DHCP servers is asking for trouble, consolidate them both onto the Windows box, you will have to manually create a new scope to replace the routers DB, as so far i don't know of a way to to transfer from a router to a server.
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by:bilbus
ID: 16955904
i would keep the two dhcp servers

as long as each one has its own scope (150-200 and 1-150) your fine. Also make sure the settings are identical. Kind of silly to have each dhcp giving out diffrant dns servers.

Two dhcp servers are nice just incase one of them fails to start. Most people do a 70/30 or a 80/20 split, so your primary dhcp (say your 2003 box) would have a scope of 20-180 or so, and 181-253 for the router.

are you using your internal dns server as the only ones listed in dhcp's dns? no isp servers should be in there. If you use ras server, you can choose a dns (your internal dns) to be handed out to clients.
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by:psk1
ID: 16955936
I'm using RAS.  I just noticed that it is using a static address pool of its own (192.168.1.200 to 192.168.1.249) for clients, so that explains my remote IP of 192.168.1.206 ...  It is set to use a second Ethernet adapter in the server to assign DNS, etc. settings, and the TCP/IP settings in that router are set to use localhost as DNS (which is correct).  However, my remote PC is unable to locate resources on the network by DNS name.
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by:psk1
ID: 16955939
"TCP/IP settings in that router" should read "TCP/IP settings on that adapter"
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by:Jay_Jay70
ID: 16955947
for VPN access even with RRAS you often need to edit the lmhosts to get name resolution cranking
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by:bilbus
ID: 16955956
as for ras, let dhcp assign addreses
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by:psk1
ID: 16955961
As I understand it:

The router passes VPN traffic through to the IP (which is handed out by the DHCP server on the router) of the box running RAS, which hands out addresses from its own static pool and uses the secondary ethernet adapter in its box to apply DNS settings to the remote client.

Therefore, the DHCP server running in the OS is not assigning anything to anyone.  Shouldn't I be able to disable that without any repercussions?
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by:bilbus
ID: 16955965
also if you just have a few servers you need to resolve you can add dns entrys to your external dns.
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by:bilbus
ID: 16955972
depends on how you set it up, you can allow dhcp to asign addresses or you can choose a static pool. As for secondary adapter i am not sure i use only a single one. If addapter 2 is on a diffrant subnet you could make a dhcp scope for that to
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by:CharliePete00
ID: 16956022
Two DHCP servers serving the same subnet with scopes in different IP networks (Server 192.168.0.0 255.255.255.0; router 192.168.1.0 255.255.255.0) is a bad idea.  You are inviting all kinds of comm issues that way.  Using 2 servers is a good idea for redundancy as long as their scopes serve addresses in the same IP subnet.  See bilbus' comment about how to splt that up.
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by:psk1
ID: 16956076
There are 2 servers and 2-3 remote computers accessing this network, all same subnet.  Very simple design.

The 2 servers on the LAN use IPs served from the router's DHCP scope.

Remote computers are served IPs from the static pool assigned from RAS.

The DCHP server on the Windows box is presently not doing anything, but as it serves a unique scope on the same subnet, what I'm hearing is that this is OK.

So my DNS issue with remote computers has more to do with the settings in RAS, and my DHCP issue really isn't an issue, though nor does the server's own DHCP server serve much use (so long as the router's DHCP server is up and running).

All concur?
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by:psk1
ID: 16956104
Or maybe I misunderstood CharliePete00's and bilbus' comments.

Let me re-read..
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by:CharliePete00
CharliePete00 earned 250 total points
ID: 16956220
Correct.

1.  Use internal DNS server or add hostname and IP addresses of internal machines to remote mchines' hosts files
2.  Assign addresses in same IP Network

Example

router scope 192.168.1.1 - 192.168.1.159
server scope 192.168.1.160 - 192.168.1.199
RAS scope 192.168.1.200 - 192.168.1.209
Static Range for  Servers, routers, etc 192.168.1.220 - 192.168.1.254
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