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  • AD DNS settings

    This thread might be better off in the AD section but here goes... One of my clients just recently moved to a new ISP and I reconfigured the new DNS settings into our router. Previously I had the local DNS settings on the AD DC set to its loopback address 127.0.0.1 and all of the PCs pointing to the AD DC IP address of 192.168.5.10. Once I changed the DNS info on our router to reflect the new ISP, Internet access became intermittent. It has been a few days now but I believe I was able to ping out to outside IPs but not their DNS names.

    After troubleshooting a bit, I went to each PC and set everything to DHCP (now receiving DNS from the local router address of 192.168.5.1). The server still has its local static IP address but is getting DNS from the router like all the PCs. Now I am having problems with the PCs losing their connection to the server. Every morning now, all users have to reboot to connect to the server. Also, once logging in, some users have to retype their credentials to connect to their mapped drives...

    Why won't the new ISP DNS settings on the router work with our old local DNS configuration? Is there a cache somewhere that needs to be purged?

  • #2
    Re: AD DNS settings

    You should consider:
    Setting up DHCP on the Server and turning off on the router
    Configure DHCP to give Server IP as primary DNS server
    Configure forwarders on the server to use your router and, if your ISP is unreliable, openDNS or other good public DNS servers

    Using router DHCP will mean the clients do not know about the Server as it has a static IP and the router doesnt understand it!
    Tom Jones
    MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
    PhD, MSc, FIAP, MIITT
    IT Trainer / Consultant
    Ossian Ltd
    Scotland

    ** Remember to give credit where credit is due and leave reputation points where appropriate **

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    • #3
      Re: AD DNS settings

      your domain controller should (almost) always point to itself as it's primary dns server. Don't let it get it's address assigned automatically. This is important for AD.

      your AD server is also, usually, your dns server. You should configure your forwarders on here (as ossian said) to point to A) the ISP's name servers and B) public name servers like OpenDNS or 8.8.8.8

      Move DHCP off your router, and onto your domain controller. Then, again like Ossian said, configure DHCP to issue only the IP address of the internal AD server (and your second AD server, if you have one)

      this is because:

      A) the workstations need to be able to resolve the internal addresses for the domain controller - there are lots of special DNS records that are needed - if the workstations arne't pointing to this, or something that at least knows about this, it'll start to screw them up.
      B) DNS is fairly heirachical - so having everything point to just your server, and then your server, if it can't resolve it, going onto the internet to resolve it, will decrease your traffic load.
      Please do show your appreciation to those who assist you by leaving Rep Point https://www.petri.com/forums/core/im.../icon_beer.gif

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      • #4
        Re: AD DNS settings

        Sorry for the delay in response. I had my email notifications turned off for some reason and didn't know there were any new posts. I've been monitoring our network and am ready to make the changes yall mentioned earlier. I am still confused though as to why the current settings have always worked for me until now.

        The AD DC points to itself with the default gateway IP of the router (that's handing out DHCP addresses) while the clients' DNS point to the server. I've had no problems with this configuration in the past. What is wrong with this setup?
        Last edited by Digi8; 8th December 2011, 06:02.

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        • #5
          Re: AD DNS settings

          Originally posted by Digi8 View Post
          Sorry for the delay in response. I had my email notifications turned off for some reason and didn't know there were any new posts. I've been monitoring our network and am ready to make the changes yall mentioned earlier. I am still confused though as to why the current settings have always worked for me until now.

          The AD DC points to itself with the default gateway IP of the router (that's handing out DHCP addresses) while the clients' DNS point to the server. I've had no problems with this configuration in the past. What is wrong with this setup?
          as odd as it sounds, sometimes things work ok for a long time before things go haywire. Just because it worked does not mean it's right.

          you would do yourself a huge favor to follow suggestions in this thread, setup AD intergrated DNS and DHCP on that DC, have DHCP hand out all the info , router should only do "routing" in this case and any server needs static IP

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