ISA Server DNS Issue

Posted on 2011-10-07
Last Modified: 2013-02-16
I have issu with on of ISA servers; for this server when i goung to nslookup it's going to the extenral DNS for thw WAN NIC then it cannont connect to domain and take long time to log on . Also i have other 2 ISA servers when going for the nslookup it's going to the LAN NIC DNS server. I need to ensure that the server goonig to the internal DNS on the LAN NIC.
Question by:Haetham
    LVL 51

    Expert Comment

    by:Keith Alabaster
    LVL 6

    Expert Comment

    Hi Hetham,

    You Can Do following Steps to resolve the issue/

    Check The Primary DNS Setting on Your LAN Card if its IP is other than your domain controller (DNS) then change it also check the perefred setting.

    Check also the host file for ISA Server

    Check The Rules for Allowances of DNS for client on ISA Server

    I Hope it Works

    Osama Mansoor
    LVL 51

    Expert Comment

    by:Keith Alabaster
    You do not use a host file on the ISA server when it is on a domain - ISA basics.

    Author Comment

    Dear all ; let me say it in other way: i have 3 ISA server Domain Members where the LAN nic configured with the Internal DNS and the WAN nic  configured with Rreal DNS; for 2 of this servers when i request Nslookup  it's going to the Internal DNS and on the 3rd one going to the Real DNS.
    what it the reason for the either cases ?
    I Hope it's clear now
    LVL 51

    Accepted Solution

    Let me say it the way I have already said it - you need to read the article - which will tell you that you cannot have the 'real' dns on the ISA external nics, it will not work properly. The external ISA nics MUST be blank and the internal nics point to the internal dns servers. The inetrnal DNS servers use the forwarders tab to point to the REAL dns external to your ISA's. Hopefully this is clear now. Your setup is incorrect - that is the reason.

    The likely reason why you are getting a difference between 2 systems and the tird system is that on system one and two you have the internal nic listed first in the bind order and the thirdwith tyhe external nic first in the bind order.

    However, you need to read up on how the winfows OS, DNS and networloing operates. There is no logic behind which dns the asystem will use, it is pure luck every timne it performs a lookup.

    Bottom line - read the article and you will be illuminated.

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