Zen and the Art of Internet | Page 5

ac.uk for academic sites and co.uk for commercial ones.
FQDN (Fully Qualified Domain Name)
The proper terminology for a site's domain name (somewhere.domain above) is its Fully
Qualified Domain Name (FQDN). It is usually selected to give a clear indication of the
site's organization or sponsoring agent. For example, the Massachusetts Institute of
Technology's FQDN is mit.edu; similarly, Apple Computer's domain name is apple.com.
While such obvious names are usually the norm, there are the occasional exceptions that
are ambiguous enough to mislead---like vt.edu, which on first impulse one might surmise
is an educational institution of some sort in Vermont; not so. It's actually the domain
name for Virginia Tech. In most cases it's relatively easy to glean the meaning of a
domain name---such confusion is far from the norm.
Internet Numbers
Every single machine on the Internet has a unique address, {At least one address,
possibly two or even three---but we won't go into that.} called its Internet number or IP

Address. It's actually a 32-bit number, but is most commonly represented as four numbers
joined by periods (.), like 147.31.254.130. This is sometimes also called a dotted quad;
there are literally thousands of different possible dotted quads. The ARPAnet (the mother
to today's Internet) originally only had the capacity to have up to 256 systems on it
because of the way each system was addressed. In the early eighties, it became clear that
things would fast outgrow such a small limit; the 32-bit addressing method was born,
freeing thousands of host numbers.
Each piece of an Internet address (like 192) is called an ``octet,'' representing one of four
sets of eight bits. The first two or three pieces (e.g. 192.55.239) represent the network
that a system is on, called its subnet. For example, all of the computers for Wesleyan
University are in the subnet 129.133. They can have numbers like 129.133.10.10,
129.133.230.19, up to 65 thousand possible combinations (possible computers).
IP addresses and domain names aren't assigned arbitrarily---that would lead to
unbelievable confusion. An application must be filed with the Network Information
Center (NIC), either electronically (to [email protected]) or via regular mail.
Resolving Names and Numbers
Ok, computers can be referred to by either their FQDN or their Internet address. How can
one user be expected to remember them all?
They aren't. The Internet is designed so that one can use either method. Since humans
find it much more natural to deal with words than numbers in most cases, the FQDN for
each host is mapped to its Internet number. Each domain is served by a computer within
that domain, which provides all of the necessary information to go from a domain name
to an IP address, and vice-versa. For example, when someone refers to foosun.bar.com,
the resolver knows that it should ask the system foovax.bar.com about systems in
bar.com. It asks what Internet address foosun.bar.com has; if the name foosun.bar.com
really exists, foovax will send back its number. All of this ``magic'' happens behind the
scenes.
Rarely will a user have to remember the Internet number of a site (although often you'll
catch yourself remembering an apparently obscure number, simply because you've
accessed the system frequently). However, you will remember a substantial number of
FQDNs. It will eventually reach a point when you are able to make a reasonably accurate
guess at what domain name a certain college, university, or company might have, given
just their name.
The Networks
Internet The Internet is a large ``network of networks.'' There is no one network known as
The Internet; rather, regional nets like SuraNet, PrepNet, NearNet, et al., are all
inter-connected (nay, ``inter-networked'') together into one great living thing,
communicating at amazing speeds with the TCP/IP protocol. All activity takes place in
``real-time.''

UUCP The UUCP network is a loose association of systems all communicating with the
UUCP protocol. (UUCP stands for `Unix-to-Unix Copy Program'.) It's based on two
systems connecting to each other at specified intervals, called polling, and executing any
work scheduled for either of them. Historically most UUCP was done with Unix
equipment, although the software's since been implemented on other platforms (e.g.
VMS). For example, the system oregano polls the system basil once every two hours. If
there's any mail waiting for oregano, basil will send it at that time; likewise, oregano will
at that time send any jobs waiting for basil.
BITNET BITNET (the ``Because It's Time Network'') is comprised of systems connected
by point-to-point links, all running the NJE protocol. It's continued to grow, but has
found itself suffering at the hands of the falling costs of Internet connections. Also, a
number of mail gateways are in place to reach users on other networks.
The Physical Connection
The actual connections between the various networks take a variety of forms. The most
prevalent for Internet links