DNS with multiple IP addresses

Discussion in 'Installation/Configuration' started by tristanlee85, May 20, 2010.

  1. tristanlee85

    tristanlee85 New Member

    I have created a domain www.cfcoding.com and when creating the site, I selected * for the IP address since I have my server configured for .68 and .69 IPs that I have set from my ISP.

    When creating the DNS record for www.cfcoding.com, it only gave me the option to enter in 1 up (unless I can enter in a list?). The idea is for me is if ns1.tbtech.net seem to be down, I would like it to try and resolve to ns2.tbtech.net which would be my other IP. Is that possible with the way the DNS is setup or am I thinking of a completely different piece of software/hardware to handle this?

    Here is my wizard configuration of my domain:
    [​IMG]
     
  2. till

    till Super Moderator

    First, DNS Zones normally dont start with www. So make sure that you created a dns zone for cfcoding.com and not for www.cfcoding.com. www.cfcoding.com is a A-Record of the zone cfcoding.com and not a separate zone.

    You can do round robin DNS, this means that you add more then one DNS A-Record for a given domain or subdomain pointing to different IP addresses. But round robin DNS is more a solution for load balancing and not for failover setups, as the client will get a error message if one of the IP addresses dont respond.

    For a failover setup, you use software like this:

    http://www.howtoforge.com/setting-u...ancer-with-haproxy-keepalived-on-debian-lenny

    http://www.howtoforge.com/loadbalanced_mysql_cluster_debian

    http://www.howtoforge.com/load_balancing_apache_mod_proxy_balancer

    which polls the different servers from time to time to check if they are online.
     
  3. tristanlee85

    tristanlee85 New Member

    Awesome, thanks. I did catch my error with the zoning and added 2 A-records for domain.com and 2 for www.

    The thing is, I have 2 IPs but they are on the same server so if the server is down it doesn't have a way to failover. I was aiming for the round-robin idea with the IPs since I have 2 separate cable modems and if 1 modem went down, maybe the other one is up (unless my entire cable system goes down).

    Thank you!
     
  4. tristanlee85

    tristanlee85 New Member

    Also, I realzed that looking at the zones in the image above, the A, MX, and NS records all have a period at the end. Should that be there or does it not matter either way?
     
  5. till

    till Super Moderator

    The period must be there. If you have a fully qualified domain name in dns e.g. www.yourdomain.com, it ahs to end with a dot. Of a record does not end with a dot, then its a relative domain name and the name of the zone gets appended to it.

    So in a zone cfcoding.com, these two A-Records are the same:

    www 123.123.123.123
    www.cfcoding.com. 123.123.123.123

    This naming convention is used by all major dns servers incl. BIND and mydns.
     
  6. tristanlee85

    tristanlee85 New Member

    Cool. Good to know. Thank you!
     

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