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Win 2008 server with DHCP also Netgear DHCP Server running at same time

Posted on 2011-09-11
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Last Modified: 2012-05-12
Hi I wanted to know if my Internet Netgear router that is also running as a DHCP Server, which also has Eth ports on it so when host pcs plug in they obviously can automatically be allocated an address!!!

But if Ive also setup a Win 2008 DC/Dns/Dhcp integrated with SP2 already and being set as 'Reserved Mac Address' within Dhcp, would this affect say my GPO's or the fact that as long as my host pc joins the domain then Im assuming all is ok?
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Question by:mikey250
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5g6tdcv4 earned 84 total points
ID: 36518864
You are going to have problems with that setup. Only one DHCP server needs to running on the network unless they are handing out non-conflicting IP ranges
It could cause problems with GPO if a client machine receives IP from the Netgear, and it is not on the same range/subnet, the client then will not be able to access domain resources
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by:riteheer
riteheer earned 416 total points
ID: 36518894
YOu can allow the Netgear to be your DHCP, set a reserved address for the server, and then set static address on server.  
You will disable DHCP on the server.

But if you are using AD, you will need the server to be DNS.  So that on all of your clients you can set the network tcp protocol to 'obtain ip address automatically'  
But, set the client dns server to be your DC.
You can set a forward lookup zone in the server for the netgear, this way when the clients ask for dns they will look to your DC, but for any names it cannot resolve, it will forward to the netgear.  
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Author Comment

by:mikey250
ID: 36518939
Hi 5q6tdcv4 - Hi thanks for your response now I see where most particular GPO may or may not have come from on an Intermitant basis hence going round in circles due to the setup!!:)

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by:mikey250
ID: 36518947
Hi riteheer, No I do not want my 'Netgear' to be the DHCP server although out of the box this is how it is setup or at least when the ISP provider install it for me.

I wish for my test Win 2008 DC/Dns/Dhcp - to be the 'Main server' as all other settings are fine!!

Im not sure how to stop DHCP handing out addresses on the Netgear as Ive already opened up the 'Gui' and currently looking!!
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by:riteheer
riteheer earned 416 total points
ID: 36518966
If you can't find it, get me the model number I'll see if I an help. You will definitely need to disable one or the other. It really doesn't make any difference which one.  I find it's often easier to run dhcp from the isp router because they tend to go down, and when I put a new one in, I don't have to go in and turn it off again....
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Author Comment

by:mikey250
ID: 36518972
Hi ritehear It looks like it is:

Netgear
VMDG280
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Author Comment

by:mikey250
ID: 36518990
I think Ive found it in the GUI under 'LAN IP', there was an option that said 'Dhcp Server Yes or No' So Ive selected No!  I may have to reboot the 'Netgear' as the IP Addresses appear to still be there as I would have expected them to disappear or dimm out or something.

I will keep it in mind that you said:

I find it's often easier to run dhcp from the isp router because they tend to go down, and when I put a new one in, I don't have to go in and turn it off again

As I did wonder about this scenario but never did it until now!!
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Author Comment

by:mikey250
ID: 36519003
Hi riteheer,  Ive just checked again 'No' meant to add addresses Manually so this was not the option!!!

Ive just read:

DHCP Server: Choose Yes to enable the DHCP Server on your gateway and assign IP addresses to computers on your LAN automatically. Choose No to assign IP addresses manually, or if you have another DHCP server on your network. Note: If you disable the DHCP server, you will need to assign your PC a static IP address in order to reconnect to the gateway and enable the DHCP server again.

Not sure where to 'Disable' the server as stated above!!!?
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by:riteheer
riteheer earned 416 total points
ID: 36519004
Yes that should be what you are looking for under the LAN IP, and I would recommend rebootting, and then you will need to release and renew the ip's on the clients.  They won't just quit using the current ip's until the lease expires.

I've set a few smaller networks in my job. 30 machines or less. And having DHCP on the router has another advantage as well, in the event that I need to take the server off line temporarily, all I have to do is reset the dns on the clients to give them internet access while the server is down.
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Author Comment

by:mikey250
ID: 36519017
Yes your right by selecting 'No' and rebooting everything should then allow automatically the 'Netgear router' to be 'Disabled' automatically and as I have already a 'Static IP Address' on the server which is currently rebooting, this should hopefully resolve my other GPO issues which have been sending me crazy, one minute work and next not!!!!!!!!
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Author Comment

by:mikey250
ID: 36519036
Hi riteheer, So when small to medium businesses run an SBS 2003/2008/2011 server I automatically assumed that everyone setup 'DHCP', but Im assuming this would be down to the IT Professional who set it up although as you say:

and then you will need to release and renew the ip's on the clients.  They won't just quit using the current ip's until the lease expires.

'I've set a few smaller networks in my job. 30 machines or less. And having DHCP on the router has another advantage as well, in the event that I need to take the server off line temporarily, all I have to do is reset the dns on the clients to give them internet access while the server is down.'

So really if there are other LANs within a companies network, then Yes DHCP can be used as expected, but when at the edge of the network ie connected directly to the internet your scenario would also be used even though realistically it would be down to that IT Professional for eg!!!!!!!?
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by:riteheer
riteheer earned 416 total points
ID: 36519058
I think it's a decision that the IT Pro would have to make on an individual basis.  
Another thing to consider is if you have two servers.... one of them can be a failover for the DC in case it goes down, but having the router or hardware firewall serve as the dhcp alleviates the problem again if the DC does go down.

Another scenario.  If you are a company that uses wireless, and wants to allow guest access to the sales people or other service personell who come in to your company on occasion.  I use a hardware firewall in most of the company networks, this I let do the dhcp, and if I'm using wireless I put the wireless guest access on a completely seperate network from my internal lan. This is easy if your router or firewall is doing the dhcp.

Did you find the place to disable dhcp on the netgear?
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Author Comment

by:mikey250
ID: 36519111
Hi riteheer,  According to the Netgear router, It is in 'LAN IP' where I select Dhcp Server 'Yes or No', but according to these notes below within the 'GUI' it states:

DHCP Server: Choose Yes to enable the DHCP Server on your gateway and assign IP addresses to computers on your LAN automatically. Choose No to assign IP addresses manually, or if you have another DHCP server on your network. Note: If you disable the DHCP server, you will need to assign your PC a static IP address in order to reconnect to the gateway and enable the DHCP server again.

So Ive took the understanding that setting 'No' automatically 'Disables the Netgear router' anyway...

Not sure how to check this is so though!!

Thanks for your useful comments though!!
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by:riteheer
riteheer earned 416 total points
ID: 36522427
Actually that is the 'NO' that you are looking for.
The precautions are such because the only way to get back into that router is if you are on a computer with same sub address as it's ip.
For instance if the router address is: 192.168.1.1  It will give out IP addresses to your computer at 192.168.1.2 thru 254 or whatever range is set by default.
   Now when you turn off the DHCP server, by selecting NO, it will no longer give out addresses.  Which is what you are shooting for.  But the caution they are giving you is, if you are using another range of addresses in your network, you won't be able to just plug in like you did and access the router.
    You will want to make sure that your server dhcp is using the same range.... 192.168.1.x   you will want to make sure your server doesn't have the same ip address as the router.  You will want to make sure that your server doesn't give out the same address as the router: 192.168.1.1 in this example.  
   If after you turn off the dhcp in netgear, and you want to access it, you will be able to do so, if the network you set up uses the same range, and the router's address is reserved.  
   If after you do this, you decided that you want to access the router with a computer plugged directly into it, you will have to make sure the computer you are using has a static ip address assigned that does coincide with the netgear address, but doesn't conflict.  IN other words, if you took the router and unplugged it from everything, and wanted to plug in a laptop and access it, you would need to connect the laptop, set a static ip of something like  192.168.1.2 and then access the netgear....
   I hope I explained that good.....
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Author Comment

by:mikey250
ID: 36522854
Hi riteheer,  Yes I did choose 'No' and what I did to test that my DC Server is the master, was to switch on host pc which did not allow me to logon to the internet, but as soon as I switched on my server the host pc allowed internet access.

Yes 'Netgear and Host pc and Server' are on same subnet!!  because if server is on a different subnet then internet access will not be allowed nor router access as you say so I agree!!!

Yes your explaination is perfect!!!

appriciated - Job done!!
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Author Closing Comment

by:mikey250
ID: 36522883
All done with sound advice!!!
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Expert Comment

by:riteheer
ID: 36522992
Mikey,
  Really glad it all worked out!  Have a great day!
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