Internet will not work unless IP address is set ?!?

Question

So we have a server and few work stations. Everything worked via WIFI untill it stopped, no internet access. The IP address was set to obtain automatically. NOW you have to set the IP addresses, subnet, etc etc. to each laptop in order for it to connect to the internet. Putting it back on Obtain Automatically will lose internet connection.

What is going on ?!

Answer 1

Just wanted to clarify the "Can I have more that one DHCP server running?" question...



(excerpted from the link at the bottom)



DHCP on a simple network works using the DORA principle.



Discovery - the client broadcasts a message on the local network segment its connected to, to discover available DHCP servers.



Offer - a suitably configured DHCP server receives a request from a client, and offers it an address from its pool of available addresses.



Request - The client replies to the offer, requesting the address received in the Offer.



Acknowledgement - The server acknowledges the request, marking the address as used in its pool of addresses, and informs the client of how long the address lease is valid for, and any other information needed.



Any device on a network segment can be a DHCP server; it doesn't have to be the router or the domain controller or any other "special" device on the network.



When the devices on your network first request an IP address or reach the end of their leases (or you force them to check their lease is still valid) they will simply broadcast a request for a DHCP server, and will accept an offer from the **first** DHCP server to reply. This is important to remember as we look at the options for multiple DHCP servers below.



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If you want to use 2 DHCP servers:



1. Make sure your router's LAN IP is static IP (say, 192.168.1.1)

2. Set your router's LAN DHCP range to: 1.11 thru 1.127 with a /24 mask. (Leave room for static IPs)

3. Make sure all static devices (servers, routers, etc.) use the range 1.2 thru 1.10 (or however large you want the range to be -- just be sure there are no overlapping ranges)

4. Now set your 2008 Server's LAN DHCP range to: 192.168.1.128 thru 1.254 with a /24 mask.

5. Both DHCP functions will use the same Default Gateway and DNS info.



Now your DHCP servers won't fight each other. Just make sure your Lease values aren't too long, causing IPs to be reserved unnecessarily.

Answer 2

Normally you should have only one DHCP server running on a network segment. This should be in the router. If you do configure a DHCP service other than in the router, then you need to ensure that this provides the correct gateway and DNS server addresses as well as allocating valid IP addresses for the network segment to the requesting devices.



However, the server in the router could be disabled and you could have a DHCP service running in a computer on the network. This must offer the router as the gateway, assuming the router is on the same network segment. Also, the DNS address provided by the server must point to a valid DNS server. Normally this will be the router, but it can be any accessible DNS server on the Internet. If the DHCP server provides the address of an Internet DNS server that is no longer avail, then this will cause problems.



For a proper diagnosis you will have to provide the IP, gateway and DNS server addresses and the network mask that a laptop gets when it uses DHCP, and also the manual addresses and mask you are using to make it work.



Following the update to the question, it seems as though the Server 2008 is providing the DHCP service. What happens if this is disabled and the DHCP server in the router is used instead? Does it work correctly when the router provides the service?



What is the purpose of the DHCP service in the Server 2008?

Answer 3

Your router is unlikely to request an IP address from its LAN side. If you want to use the server as the DHCP server I recommend giving the router a static IP address x.x.x.1 and make this your default gateway. Give your server a static IP address, and make your DHCP server is providing the routers IP address as the default gateway address. You will also need to assign DNS addresses via the server.



It might be easier if you just turn off DHCP on the server and let the router do it. I would still give the server a static IP address and remove that IP address from the DHCP address pool on the router.

Answer 4

Sounds like the DHCP server on your router has been turned off. The DHCP server replys to any computer asking for an automatic IP address and sends it the details.

Answer 5

What kind of Server are you running... is it running a DHCP Server which is conflicting with router's DHCP server?



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Clients has a Lease time... that's when they will request.... turning of DHCP doesn't make client revert to other DHCP server...



You would have to turn off DHCP on Server then restart network adapters... for them to get DHCP from correct Server.

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And I already explained how to have them both working together...



Where IP's address comes from isn't not important as long as they Match are correct... But Server 08 Must run DNS to run AD.