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    Single DNS server returning old & new addresses during propagation?


    I have a domain change that has been propagating since around midnight last night. In the past things have stabilized in just a few hours, but this one is taking much longer. One thing I'd like help with is explaining how a specific DNS server can return both the old and new addresses at random with distinct requests in rapid succession (see below). The TTL is 24 hours. I have a test script which uses dig to make the same query of all the name servers in a Linux system's resolv.conf. In the example below, two servers are queried three times in a row for the domain cathouseonthekings.com and DNS server 68.94.156.1 returns first the old (74.54...) then the new (174.122...) and then the old address again:

    ---- Checking 68.94.156.1 ----

    ; <<>> DiG 9.7.4b1-RedHat-9.7.4-0.2.b1.fc14 <<>> @68.94.156.1 cathouseonthekings
    .com any +nocmd +nostats +noques +nocomments +author
    ; (1 server found)
    ;; global options: +cmd
    cathouseonthekings.com. 5263 IN A 74.54.218.210
    cathouseonthekings.com. 7056 IN NS ns884.hostgator.com.
    cathouseonthekings.com. 7056 IN NS ns883.hostgator.com.
    ---- Checking 68.94.157.1 ----

    ; <<>> DiG 9.7.4b1-RedHat-9.7.4-0.2.b1.fc14 <<>> @68.94.157.1 cathouseonthekings
    .com any +nocmd +nostats +noques +nocomments +author
    ; (1 server found)
    ;; global options: +cmd
    cathouseonthekings.com. 750 IN A 174.122.89.82
    cathouseonthekings.com. 24993 IN NS ns1.cathouseonthekings.com.
    cathouseonthekings.com. 24993 IN NS ns2.cathouseonthekings.com.
    dnscheck cathouseonthekings.com |more
    ---- Checking 68.94.156.1 ----

    ; <<>> DiG 9.7.4b1-RedHat-9.7.4-0.2.b1.fc14 <<>> @68.94.156.1 cathouseonthekings
    .com any +nocmd +nostats +noques +nocomments +author
    ; (1 server found)
    ;; global options: +cmd
    cathouseonthekings.com. 2581 IN A 174.122.89.82
    cathouseonthekings.com. 13222 IN NS ns2.cathouseonthekings.com.
    cathouseonthekings.com. 13222 IN NS ns1.cathouseonthekings.com.
    ---- Checking 68.94.157.1 ----

    ; <<>> DiG 9.7.4b1-RedHat-9.7.4-0.2.b1.fc14 <<>> @68.94.157.1 cathouseonthekings
    .com any +nocmd +nostats +noques +nocomments +author
    ; (1 server found)
    ;; global options: +cmd
    cathouseonthekings.com. 10561 IN A 174.122.89.82
    cathouseonthekings.com. 28901 IN NS ns1.cathouseonthekings.com.
    cathouseonthekings.com. 28901 IN NS ns2.cathouseonthekings.com.
    dnscheck cathouseonthekings.com |more
    ---- Checking 68.94.156.1 ----

    ; <<>> DiG 9.7.4b1-RedHat-9.7.4-0.2.b1.fc14 <<>> @68.94.156.1 cathouseonthekings
    .com any +nocmd +nostats +noques +nocomments +author
    ; (1 server found)
    ;; global options: +cmd
    cathouseonthekings.com. 5718 IN A 74.54.218.210
    cathouseonthekings.com. 8649 IN NS ns884.hostgator.com.
    cathouseonthekings.com. 8649 IN NS ns883.hostgator.com.
    ---- Checking 68.94.157.1 ----

    ; <<>> DiG 9.7.4b1-RedHat-9.7.4-0.2.b1.fc14 <<>> @68.94.157.1 cathouseonthekings
    .com any +nocmd +nostats +noques +nocomments +author
    ; (1 server found)
    ;; global options: +cmd
    cathouseonthekings.com. 5259 IN A 74.54.218.210
    cathouseonthekings.com. 7052 IN NS ns884.hostgator.com.
    cathouseonthekings.com. 7052 IN NS ns883.hostgator.com.
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    That is usually a sign of load balancing. While the IP you are querying is a single IP, there may be multiple separate DNS servers behind that IP address. This does make troubleshooting more complicated due to the variables, but the way to tell is by looking at the TTL's. When you query in rapid succession, after a little while you can make an educated guess as to how many different DNS servers are answering. This is because in most load balancing environments, cache isn't shared. Most large companies do this, especially public DNS such as OpenDNS and Google DNS.
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    Thank you.


    Thanks for the prompt reply. That makes perfect sense.

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