Nameserver/DNS updating

Discussion in 'General Mac Discussion' started by yg17, Oct 14, 2005.

  1. yg17 macrumors G5


    Aug 1, 2004
    St. Louis, MO
    The last time I had to deal with updating nameservers for a domain name, it took a couple days for the DNS to refresh and the domain point to the new server. That was a couple years back.

    Today I was helping a friend move his site from an old host to a new one. A little less than an hour ago, I logged into the domain registrar's site and pointed the domain name to the new nameserver. Of course, the change wasn't immediate. But just a few minutes ago, I went to the new domain, and lo and behold, it was updated. So what used to be a 24-48 hour deal is now 24-48 minutes it seems.

    My question is, since when were nameserver changes this fast? It's much more convienent than the way it used to be with the wait.
  2. belvdr macrumors 603

    Aug 15, 2005
    It can still take up to 24 hours for the DNS entries to propagate to all DNS servers.

    You can set a Time-To-Live (TTL) in the zone file and have it updated as often as you like. Most DNS administrators allow you to specify your own TTL, but some actually ignore the authoritative TTL and specify their own. It seems that, in your case, the TTL was either fairly low and your DNS admin allowed the update, or you just happened to query the DNS entry when the DNS cache expired.
  3. ToastyX macrumors regular

    Oct 4, 2005
    DNS doesn't work the way many people seem to think it does. DNS doesn't propagate or refresh or anything like unless you're talking about master and slave name servers.

    Name server changes used to take longer because the name servers that delegate .com and .net domain names used to be updated only twice a day, and changes didn't always make it until the update after the next update, which means it used to take up to 24 hours for changes to take effect. Since September 2004, name server changes for .com and .net domain names have been immediate. Any delays beyond that are due to caching.

    DNS records are looked up on demand (when requested) and cached for the length of time specified by the name server that returned the record. The length of time is called the time to live (TTL). The name server (NS) records for .com and .net domain names have a TTL of 48 hours. If the DNS servers you're using (most likely your ISP's unless you changed them) and your local resolver's cache (lookupd in Mac OS X) don't have the old NS records cached, you will see the change immediately unless the address (A) record is still cached, otherwise you will have to wait until the cache expires to see the change. This means it can still take up to 48 hours for you to see the change, but since you no longer have to wait for the name servers that delegate .com and .net domain names to update, it's possible to see the change much sooner.
  4. belvdr macrumors 603

    Aug 15, 2005
    My talk of propagation was termed incorrectly. I was referring to caching of an A record.

    And, if you are the admin of a zone, I don't necessarily have to abide by your TTL.. I can override that, and force your TTL to be anything I want.

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