DNS: can yuou have multiple IPs in use?

Posted on 2006-03-27
Last Modified: 2010-03-19
we are about o move location and it would be really handy if we could get several servers to have multiple dns records,
current site has totally differnt external ips to new site.

email, fine i just add mx records with differnt costing.

but not sure about (A) and www and PTR records

site a
web server =
ptr =

site b
webserver =
ptr =

same physical server but need it to work at either site  (test on a tuesday) move for real on the friday, as there is a lead time both running with faiilover is preffered.

isp can only offer round robin on www records,  

yet to have an answer on reverse lookups

what other ways could you get round this, surley large farms of web servers have one domain name and multiple IPS?

Question by:mhamer
    LVL 30

    Expert Comment

    the answer to your question is YES
    LVL 30

    Accepted Solution

    duplicate your reverse zone.. then duplicate your forward zone with the NEW IP....

    update the server data files..and that's all you have to do.
    LVL 11

    Assisted Solution

    by:Steve Agnew
    Whenever a client gets multiple responses from DNS for a server it chooses one at RANDOM.  Do an NSLOOKUP for and you'll see what IE uses to pick.  I don't think it actually uses a matrix to choose.. it might prefer one on it's network but if they are all 'remote gateway' away I think it's just RANDOM from what I have heard.
    LVL 4

    Assisted Solution

    Back to the first answer...  YES.  BUT, reverse dns doesn't work the same.  When a machine resolves an IP address, it will give the address RoundRobbin by default and alternate between the available IPs, but if the first ip fails, it reverts to the second.  So it will work, however it may be a little buggy.  Additionally Reverse DNS will not work that way.  DNS is a one to many database relation.  You cannot do Many to one.  If you setup multiple reverse records, the reverse looks will fail %50 of the time.

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