E^2:
Here is a slight correction on DNS and the inclusion of “.com”. The appending of .com is a function of the web browser, not of DNS. This will always be the case due to the structure of a url and a fully qualified domain name.
For anyone interested, here is a little bit on how FQDN (Fully qualified domain names) actually work. As an example,
is comprised of three domains.
The first is the root level domain, represented by ".", which is frequently omitted. The Root servers DNS contain NS (Name Server) entries for all of the Top Level Domains. Last time I checked, there were 13 root DNS servers. In the example of "
the "." is omitted.
That leads me to the next level is the Top Level Domain, this level includes "com", "gov", "net", "org", and many others. Each of these domains has a set of DNS servers with NS records for ALL of the domains at the level below them. In the example of "
the top level domain is "com". Generally speaking, most DNS servers have the addresses for the common top level domains automatically cached, therefore, they don't need to refer to the "." server to find the DNS servers for "com".
The next level down is the individual domain level. The DNS servers for the individual domain are the ones controlled either by the domains registered owner or by a hosting service acting on behalf of the registered owner. These DNS servers hold many different types of records. The types of most interest are the A (Address) records that tie host names to a specific IP addresses, CNAME (Canonical Name) records, which tie alias names to host names, and MX (Mail Exchanger) records, which direct SMTP traffic to an email server. The DNS can also hold NS records for sub domains. This is actually very common in large enterprises and educational institutions. In the example of "
"www" is most commonly a CNAME record pointing to an A record within the domain.
Now, with that explained, I want to revisit the idea of not using "
I am against omitting "
The whole concept of browsing the World Wide Web is to go to connect to a specific host who is capable of supporting the HTTP: protocol, and there by sharing web sites. By omitting the "
you are not only being lazy, but ambiguous as to the host you truly are interested in connecting to. Main domains actually have multiple hosts with distinct content on each. In our example of "
we are specifically interested in connecting to "
We may, at another time, be interested in connecting to "north", as it provides specific information about the mystical "North" project. In this case, we would certainly need to include the host name and type "north.blah.com".
I must admit, that I did fail to mention the fact that even typing in "
is incomplete. The actual URL should include the name of the file being accessed. For most web servers, a request to a domain, without a file indicated, will result in returning the default file, usually index.html.
Of course if someone really wanted to delve into the dark world of DNS, we could discuss recursive and iterative DNS queries.
-Brian-
I'm not an actor, but I play one on TV.