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  1. #1
    Join Date
    Nov 2009
    Location
    Wales, UK
    Posts
    103

    Different subnets and reverss DNS

    Hi just a quick question regarding DNS and subnets...
    When i do a dns report on my domain it displays this warning message.

    Code:
    Different subnets-WARNING: Not all of your nameservers are in different subnets
    Does this mean if i had a different ip address on ns2.mydomain.com from somewhere else that this will get rid of this message.

    ----------------

    And the next question is how do i setup a reverse DNS on my server?? Does anyone know any good tutorials on how to do it through cpanel/whm... this is the message i get on the dns report...

    Reverse MX A records (PTR) - ERROR: No reverse DNS (PTR) entries. The problem MX records are:

    Cheers
    Chris

  2. #2
    Join Date
    Nov 2009
    Location
    Wales, UK
    Posts
    103
    Right for sorting out the Reverse dns in cpanel i found this tutorial... It is really easy to follow and works a charm...

    http://forums.cpanel.net/f5/rdns-rev...ial-69349.html

    Now its just the Subnet thing

  3. #3
    Join Date
    Nov 2007
    Location
    India, USA and Amsterdam
    Posts
    2,581
    Your DNS has single point failure as you have only one DNS server running (its very common). If you want avoid this, you need to have one more fail over DNS.

  4. #4
    Join Date
    Nov 2009
    Location
    Wales, UK
    Posts
    103
    Where would i get a fail-over dns from??? Been searching Google but there's so many different things for dns its a little overwhelming...

  5. #5
    Join Date
    Nov 2007
    Location
    India, USA and Amsterdam
    Posts
    2,581
    Why not use hosted DNS of your domain registrar? Many domain registrar like name.com offer this service at no extra cost.

  6. #6
    Join Date
    Nov 2009
    Location
    Wales, UK
    Posts
    103
    Hmm.. Ill look into that now... im with enom they should do it..

  7. #7
    Join Date
    Apr 2006
    Posts
    1,128
    The subnet complaint is purely because you have two (or more) nameservers, but both are running on either the same IP or IP addresses with the same subnet.

    The reason the check (intodns.com I suspect) is flagging that up is because it assumes since the nameservers are in the same subnet, they are located in the same datacentre, so if something were to happen to that datacentre (power failure, network outage, etc), then all the nameservers would go down - hence, a single point of failure, and no one would be able to resolve to the sites you're hosting.

    This isn't inhibiting the operation of your nameservers at all, it's just a warning.

    Of course, this doesn't really make any difference at all if the services you're providing (web hosting I presume) are hosted in the same datacentre anyway, since if there was a failure at the datacentre it would knock your primary nameservers and hosting servers offline, so your redundant backup nameservers would kick in but they would be pointing to the offline hosting server anyway.

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