3 Major incorrect beliefs about Global DNS (root
DNS) servers
Until today, since I started getting into the depth of DNS some
years from now, I always thought that there are 13 major
super-computers used as a Global DNS servers which were responsible
for caching in all the domain names on the IPv4 and IPv6 internet
and that's all I knew about this matter.
Today I had to review my knowledge on the subject of DNS protocol,
BIND server etc. in order to be able to fix an issue with a newly
configured BIND dns server. In relation to that I red a bunch of
interesting articles online discussing a matters concerning root
DNS servers.
Here are two major articles worthy to read:
1.
DNS Root Name
Servers Explained for Non-Experts - by Daniel Karrenberg
2.
DNS Root servers in
the World
This blow off the myth about 13 major super-servers running on top
of backbones to serve DNS requests online. By the way it's
interesting fact that I've learned that myth from some O'reilly's
books that were explaining the Redhat Linux distrubution long time
ago.
It could be that long time ago this was true but not anymore!
As of today's date: Tue Mar 16 17:19:02 EET 2010, there are 425 DNS
root servers which are an Internet's bone today.
Interestingly enough full list of the root servers is available via
isoc.org's website along with
many more information on the subject of how root DNSes works, how
the DNS is served on the Internet as well as the RFC which explain
the proper way to implement a DNS server.
A copy of the
zonefile
containing in it all the root DNSes can be obtained via isoc's
website
Another wrong idea about Global DNS servers that I kept with me
over the years is that most of the root servers are geographically
located in USA.
A good proof to this delusion is
root-servers.org website which
contains a
wonderful Google map
with pinpointed geographical locations of all root servers
.Along with this there is a plenty of extensive information on root
DNS servers.
Another misbelief when talking about DNS servers is that the
A-root server is the main DNS server in the Global DNS
cluster.
Another good reading location concerning DNS Root servers is
The DNS Root Name
Server FAQ .