Tuesday, Tuesday, September 25, 2001, 11:57:21 AM, Dave Walton wrote:
> Could someone explain just what the root name servers do?
> I understand that my DNS Servers translate a Domain Name to an IP Address.
> Do the Root Servers just cache this information? Or do they provide another
> role? How does a resolution request get routed to the correct Name
> Server(s)?
> Why does it take up to a week for a change in registered name servers to
> take effect?
Let's follow a request:
User types a domain name www.example.com into their browser. They
send a dns query to the default nameserver in their TCP/IP
configuration. That nameserver then realizes that it doesn't know
that name, so (I'm simplifying things a bit) it sends a request to the
root server for where it can find com. It sends a referral to the
nameservers that handle com. Then the nameserver asks one of those
where it can find example.com. It then returns the nameservers the
registrant has listed for domain.com. It then queries one of those
nameservers and asks where it can find www.example.com. It also will
cache that response, and each of the previous responses, for a period
of time that is controlled by the respective operators of the zones.
The reason it can take up to a week sometimes to see changes, instead
of a couple days which is the norm, is usually because of that cache
time. Nameserver admins put much longer TTL times, which tell the
caching nameservers how long to cache the answers, than they should,
thinking it is the smart thing to do. It's not that smart, however,
since the caching nameserver will not check for that domain again
until that cache time expires.
The Verisign registry sets a cache time of 48 hours for domain
delegation requests in the gTLDs it manages. It can also take 24
hours (sometimes longer) for all 13 of the gTLD-Servers Verisign
manages to load an updated zone that contains the new nameserver
information. This is on top of the up to 12 hours it can take to get
the changes into a new zone. Plus whatever time the example.com zone
operator has set the TTL for that zone to be
So under even normal conditions, if everything works against you, it
can take up to 84 hours (or longer based on the TTL) for bad data to
expire from the cache of a nameserver and for that nameserver to be
guaranteed to get correct data.
Sounds complicated? I've simplified it somewhat. :)
--
Best regards,
William X Walsh <[EMAIL PROTECTED]>
Userfriendly.com Domains
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