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Operating System Tools

Notes Authoritative DNS Servers

Authoritative servers offer the definitive information for your DNS domain, such as the names of
servers and Web sites in it. They are the last word in information related to your domain.
How DNS Servers Find Out Your Site Information

There are 13 root reliable DNS servers (super duper authorities) that all DNS servers query
first. These root servers know all the authoritative DNS servers for all the main domains - .com,
.net, and the rest. This layer of servers keeps track of all the DNS servers that Web site systems
administrators have assigned for their sub domains.

Example: When you register your domain my-site.com, you are in fact inserting a record
on the .com DNS servers that point to the authoritative DNS servers you assigned for your
domain.

When to Use a DNS Caching Name Server

Most servers don’t ask authoritative servers for DNS directly, they generally ask a caching DNS
server to do it on their behalf. These servers, through a process called recursion, sequentially
query the authoritative servers at the root, main domain and sub domain levels to get eventually
get the specific information requested. The most frequently requested information is then stored
(or cached) to reduce the lookup overhead of subsequent queries.
If you want to promote your Web site www.my-site.com to the rest of the world, then a regular
DNS server is what you require. Setting up a caching DNS server is fairly straightforward and
works whether or not your ISP provides you with a static or dynamic Internet IP address.
After you set up your caching DNS server, you have to configure each of your home network PCs
to use it as their DNS server. If your home PCs get their IP addresses using DHCP, then you have
to configure your DHCP server to make it aware of the IP address of your new DNS server, so
that the DHCP server can advertise the DNS server to its PC clients. Off-the-shelf router/firewall
appliances used in most home networks usually can act as both the caching DNS and DHCP
server, rendering a separate DNS server is unnecessary.

When to Use a Static DNS Server

If your ISP provides you with a fixed or static IP address, and you wish to host your own Web
site, then a regular authoritative DNS server would be the way to go. A caching DNS name
server is used as a reference only; regular name servers are used as the authoritative source of
information for your Web site’s domain.

How to Get Your Own Domain

Whether or not you use static or dynamic DNS, you need to register a domain. Dynamic DNS
providers regularly offer you a sub domain of their own site, such as my-site.dnsprovider.com,
in which you register your domain on their site.
If you choose to create your very own domain, such as my-site.com, you have to register with a
company focus in static DNS registration and then point your registration record to the intended
authoritative DNS for your domain. Popular domain registrars include VeriSign, Register Free,
and Yahoo.

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