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  1. #1

    DNS & Mirroring question

    Hello,

    This is my first post and had a question about dns and mirroring.

    Here is the scenerio :

    I have my main website on server1 and it is a whm cpanel server. The website is dynamic and database oriented website.

    I have another server - server2 with whm installed on it and I wish to configure both the servers such a way that the data is synchronised on both the servers in particular intervals.

    Also I would like to configure dns redundancy in such a way that if one server goes offline for some reason, the website should be immediately resolving from the other server.

    Can anyone please guid me if this is possible in how.

  2. #2
    Join Date
    Apr 2005
    Location
    Cochin
    Posts
    2,446
    you can use rsync to syncronize your files ....not sure about fail over system though

  3. #3
    Join Date
    Feb 2005
    Location
    India
    Posts
    911

  4. #4
    Join Date
    Nov 2004
    Location
    Dallas
    Posts
    739
    rsync is the option for syncronizing files, but for example I think load balancers can help you to redirect the traffic

  5. #5
    Inorder to synchronize the servers, Kindly use the option Dns Cluster Management in WHM. Check with the link http://www.cpanel.net/docs/dnsclustering-quickstart/ and follow it up.

    cPanel also provides script that performs synchronization between DNS peers. The script is located in the cPanel /scripts directory.

    /scripts/dnscluster

    Usage: dnscluster <action> <zone>
    Actions:
    syncall - make sure all dns zones are
    in sync within the cluster. If the zones
    are out out of sync, the one with the largest
    serial number will be copied to all servers.

    syncalllocal - make sure all dns zones are
    in sync within the cluster. If the zones
    are out out of sync, the one with the largest
    serial number will be copied to all servers.
    Only the local server's zone database will be updated.

    synczone <zone> - sync one zone
    If the zone is out out of sync, the one with the largest
    serial number will be copied to all servers.

    Let me know if you need any further help on this.
    liwiplus Team,
    http://www.liwiplus.com
    The Support Sages

  6. #6
    Hi,

    thanks for your suggestions. Actually I wanted to configure my website in such a way that my website should have multiple A records so that if one server goes down, it should resolve from different server.

    Thanks liwiplus for the information. Well dns clustering will be of no use if my main server goes down, its no use if the dns from other server is up, unless there is data on the other server. I hope my statements make sense I am sorry if my concepts are not clear.

  7. #7
    Join Date
    Jul 2006
    Location
    Sterling, VA
    Posts
    19

    IP failover

    your looking for a monitoring and failover solution - so that if one server goes down you route to an alternate IP address

    You can do this through a few companies - mine included but there are hardware solutions you can configure to failover as well. Cisco has one I know.

    Hope that helps
    James Dobbs
    Biz Dev Director
    Neustar UltraDNS
    (703) 547-6001

  8. #8
    For Multiple A records ,I suggest better you have 1 Dnsserver and 2 WebServers and have to Set priority for A record in the DnsServer, so that if once webserver IP fails, it will switch to other server. Also You need to check this with your domain registrar for setting priority for your webserver IPS.

    If you need any further assistance mail me [email protected]
    liwiplus Team,
    http://www.liwiplus.com
    The Support Sages

  9. #9
    Join Date
    Feb 2005
    Location
    Australia
    Posts
    5,842
    Quote Originally Posted by kpicacho
    The website is dynamic and database oriented website.
    This is potentially your biggest problem. A dynamic web site that can be updated from 2 independent servers will need some serious custom programming to keep the updates in sync.

    It becomes much easier if you designate one server the master and do all updates on this, syncing at intervals to the slave. You still need to deal with changing the state of web site (slave read-only, master read-write) but it becomes much more doable.

    In this situation you cannot use multiple A records - there are no priorities on A or NS records like there are on MX so if you have 2 A records your visitors will go at random to both servers. Also you can't get cute with different nameservers pointing to different web servers - all nameservers must give the same information because any of them can be used.

    So what you need is dns failover - where you monitor all servers and if the master goes down, automatically change dns records to point to the slave. Be aware that this has some issues - dns records are cached by ISPs, sometimes for much longer than the TTL you set on them, so after you change dns some visitors will continue to get the old information for a time.

    I don't think the CPanel clustering system does failover (can anyone confirm?) so to do this you have the choice of one of the many dns services (eg. zoneedit / dnsmadeeasy) or brewing up your own system to monitor and change dns records as required.

    HTH
    Chris

    "Some problems are so complex that you have to be highly intelligent and well informed just to be undecided about them." - Laurence J. Peter

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