windows server 2012 no internet acces (DNS not responding)

[coolmen815]

Hello,

I have a problem with my server. I installed AD DHCP and DNS on it. I turned DHCP on my router off (Arcadyan VGV7519) so that the server is now giving the IP adresses. Everything was working until i restarted my router and the server had no internet acces. It wouldn't even ping to any other PC's in my network. After doing some stuff the DHCP was agian giving IP adress and i could ping agian to other computers but NOT to my router and the DNS is still not responding.

I read somethings that i need to add my ISP DNS server to the DNS forwarders list. So i added them but they are not responding even Google's DNS (8.8.8.8) is not responding. Im killing myself here and i don't know what to do. Please help me

Sorry if this is a bit unclear my english is not that good.

 

[Alabalcho]

- your router' LAN address should be outside of Win2012' DHCP server scope, yet on the same subnet. Same for your server. This will ensure that it is reachable. So, let assume:
Router IP: 192.168.0.1
Server IP: 192.168.0.2
DHCP Scope: 192.168.0.100 .. 150 (this will leave some IP addresses for other fixed IP devices, like printers, WEB cameras etc)
- DHCP server must assign your router' IP address as default gateway for it's clients
- DHCP server must assign itself as DNS server, and being properly configured. Check AD requirements for that

So, in end of all - you must be able to ping withing your network the router (.1), the server (.2) and any client. DHCP server must be authorised by the AD in order to work, (if my memory servers me).

 

[coolmen815]

Okay so if i get this right my routers IP adres is 192.168.1.254 and my server is 192.168.1.1 so my DHCP scope should be for example 192.168.1.2 - 192.168.1.253? Because no i have 192.168.1.1 - 192.168.1.254 so that should be the problem.

 

[Alabalcho]

This is probably not a problem right now, but at least bad decision. Check DHCP server console to see what addresses have been given.

Also - it is bad security practice to allow your DHCP server to give way more addresses than expected (that is, if your office has 10 PCs, and you expect no more than 10 wireless devices, set your DHCP to give out 25 addresses).

 

[coolmen815]

Thnx for your answer but my problem still persist. I had to reinstall my server agian because i messed it al up. So i reinstalled DHCP DNS and AD agian. It was agian working it was leasing IP adress and all my clients had internet. But when i woke up this morning nothing was working agian. My server had no internet acces and could not ping the gateway (router) and all my clients didnt have internet acces aswell. The problem is the DNS server. When i change the dns server on one of my clients to my router it has internet acces agian.

Could the problem be that i have only 1 internet cable in my server instead of 2? I dont know what to do i did everything you said my server is out of the scope aswell my router.

 

[Alabalcho]

The DNS would not prevent you from pinging using IP addresses. There is no requirement for your server to use two network cards (unless that server is acting also as a Internet gateway).

You said, you have Internet if you change DNS server on a client. Are you changing the IP address as well? Are you able to ping your server from a client?

 

[coolmen815]

When i change DNS server on a client i do not change the ip adress. Only the DNS server. And when i change it to my router im not able to ping my server. But when i change the DNS back to my server then im able to ping it agian. It looks like that i doesn't sign itself an IP adress

 

[coolmen815]

Anyone? I really need some help. My server is also not directly connected to my router but to a switch is that a problem?

 

[Alabalcho]

You have some serious IP addressing problem. Irrelevant of who is DNS server, you should be able to ping (by IP address) between every client, server and router. Make sure that IP addresses you are allocating are from same network.

Once you confirm that your IP addressing is OK, you can start fighting the DNS/AD integration. But first make sure you can ping using IP addresses only.

 

[coolmen815]

It's working now i don't know how but it's working. Thank you for your help