Page 130 - DCAP602_NETWORK_OPERATING_SYSTEMS_I

Network Operating Systems-I

notes 3. Internet Name Resolution: LAN workstations and other desktop PCs need to send Internet
domain name resolution queries to a DNS server. The DNS server most frequently used
for this is the ISP’s DNS servers. These are often the DNS servers you specify in your
TCP/IP configuration. You can have your own DNS server respond to these resolution
queries instead of using your ISP’s DNS servers. My ISP recently had a problem where
they would intermittently lose connectivity to the network segment that their DNS servers
were connected to so they couldn’t be contacted. It took me about 30 seconds to turn one
of my Debian systems into this type of DNS server and I was surfing with no problems.
On this page we’ll refer to these as simple DNS servers. If a simple DNS server fails, you
could just switch back to using your ISP’s DNS servers. As a matter of fact, given that you
typically specify two DNS servers in the TCP/IP configuration of most desktop PCs, you
could have one of your ISP’s DNS servers listed as the second (fallback) entry and you’d
never miss a beat if your simple DNS server did go down. Turning your Debian system
into a simple DNS server is simply a matter of entering a single command.
Don’t get from this that you need three different types of DNS servers. If you were to set up a
couple authoritative DNS servers they could also provide the functionality of LAN and simple
DNS servers. And a LAN DNS server can simultaneously provide the functionality of a simple
DNS server. It’s a progressive type of thing.
If you were going to set up reliable DNS servers or a simple DNS server you’d have to have a
24/7 broadband connection to the Internet. Naturally, a LAN DNS server that didn’t resolve
Internet host/domain names wouldn’t need this.
A DNS server is just a Debian system running a DNS application. The most extensively used
DNS application is BinD (Berkeley Internet Name Domain) and it runs a daemon called named
that, among other things, responds to resolution queries.



Case Study net Domain name system gets 10 applications

s part of the process of expanding the Internet’s domain name system, the
Internet Corporation for Assigned Names and Numbers (ICANN) has received
A10 applications for sponsored top-level domains(sTLDs). Domains that have been
applied for include `.asia’; `.post’; `.mail’; `.travel’; `.tel’ and `.jobs’.
While an un-sponsored top-level domain operates under policies established by the
global Internet community through the ICANN process, a sponsored top-level domain
is a specialised one that has a sponsor representing the specific community that is most
affected by the top-level domain.
So, for instance, the Bern-based Universal Postal Union has applied for the `.post’ top-
level domain, while the New York-based The Travel Partnership Corporation, a non-profit
consortium of international travel organisations, has applied for the `.travel’ top-level
domain.

Other applications received by ICANN include those from the Hong Kong-based DotAsia
Organisation Ltd for the `.asia’ top-level domain, the Anti-Spam Community Registry’s
application for the `.mail’ top-level domain and that of the US-based Society for Human
Resources Management for `.jobs’. Interestingly, the Toronto-based International
Foundation for Online Responsibility has applied for the `.xxx’ top-level domain, while
there are two applications for the `.tel’ top-level domain.
The applications are currently open for `public comment’, which will close on April 30.
Once this is over, an independent evaluation panel will review the applications for the
Contd...

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