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Contents
What IS the Internet?
Computer Names
FQDN - Fully Qualified Domain Name
Computer Addresses
URL - Uniform Resource Locator
DNS - Domain Name Services
What does this have to do with making web pages?
Read This
Like it says, Evil Technical Details. However, if you want to understand how you create and upload a web site, and how people are able to view it, you have to understand this stuff. More importantly, if your web site is NOT visible, or looks funny, you need to know some reasons why that might be the case. Otherwise, how do you even begin to fix it?
If you are still wondering what this has to do with making web sites, click here.
What IS the Internet?
The Internet and world wide web is a huge network of computers. A network is two or more computers that are physically connected so they can share files and other resources (like a printer, or fax).
The Internet consists of millions of computers connected by millions of miles of cables. When you look at a web site, you are looking at some files on some computer's hard drive, somewhere in the world. That computer might be across the room or across the ocean. It makes no difference - you can still see the files on it, if everything is working properly.
Yes, wireless networks exist, but they are still not as common as wired networks, and the internet as a whole is a long way from being wireless. Wireless connections accomplish exactly the same thing as cabling anyway: a wireless network card broadcasts a signal which is picked up by a receiver (a wireless hub, switch, or router). From that access point the signal is sent on to the internet. Eventually cabling has to be involved - for the time being, and, I suspect, for some time to come.
Back to ContentsHow Computers Find Each Other: Names and Addresses
Names
Every computer on a network has a first name (hostname) and a last name (domain), and many have nicknames (aliases).
The name of a computer (properly referred to as the "hostname") can be almost anything, such as "fred", "darkstar", "21-4-16-hike". They can also have nicknames, or aliases. For security, you don't want the world at large to know the real names of your computers. A very common alias for web servers is www; a very common alias for FTP servers is ftp, etc.; (see below).
The Fully Qualified Domain Name (FQDN)
The full name (hostname+domain) is properly called the Fully Qualified Domain Name (FQDN), for example www.google.com.
No two computers in the world have the same FQDN, although many share the alias hostname www. There is only one machine in the world answering to the name of www.google.ca (but see below about aliases). The "first name" (the hostname) is the left-most part of the FQDN, www. The "google.com" part is also called the domain. Graphically:
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The domain can be thought of as a "family" or "last" name. That is, if you hear about several computers, called www.google.com, ftp.google.com, and support.google.com, they are probably all run by the same company. The same company might also be responsible for www.google.ca, www.google.net, etc. Or not. Things can get very complicated. I can't get into the details here.
It's possible for an entire FQDN to be a nickname. For example, I might have a web site at clubweb.interbaun.com/~mward; I could register mward.ca as a domain for myself; then I could just make www.mward.com an alias for clubweb.interbaun.com/mward. Then, any computers trying to find www.mward.ca would simply be redirected to clubweb.interbaun.com/~mward. End users would never know the difference.
A single computer can have multiple aliases, too. For example, support.redhat.com, sales.redhat.com, and www.redhat.com might be all the same machine.
Aliases can also work the other way around: a single FQDN might actually be more than one machine. This appears to contradict what I said above (no two machines have the same FQDN), but that's not really what's happening. Very busy web sites, like Google, may have more than one box answering to a single FQDN. They get so much traffic that no single machine could deal with it, even with top-of-the-line hardware. What's happening is that queries to www.google.ca are actually distributed to several machines.
Back to ContentsAddresses - every computer on a network has one
Every computer on the internet also has an address, which is a series of four numbers between 0 and 255, separated by periods, such as:
192.168.3.154
This is an IP address. IP means "Internet Protocol" (see below). No two computers on the internet, or even a private network, have the same IP address. Each number is called an octet; IP addresses are also called dot quads.
URL - Uniform Resource Locator
When you add some gibberish to the front of a FQDN, you get a URL, like this:
http://www.google.com
The gibberish is the protocol, http. A protocol is a set of rules that defines how computers talk to each other for certain purposes. Think of it as a language computers speak. The Internet Protocol is the backbone of the web and internet as a whole. Other protocols might be considered dialects. You may have heard of POP (Post Office Protocol), FTP (File Transer Protocol), SMTP (Simple Mail Transport Protocol), and others. The http (HyperText Transfer Protocol) protocol defines the rules for dealing with web pages. Most browsers do not require you to type "http"; they will automatically detect the protocol. The colon and two slashes (://) separate different pieces of information (the protocol and the FQDN).
DNS - Tying it all together
URLs exist for the benefit of humans: www.google.ca is far easier to remember than 64.233.167.99. Computers themselves couldn't care less about URLs. They need to know the other machine's IP address. That's what DNS servers are for.
DNS is for Domain Name Services. DNS servers are the telephone books of the computer world. They contain HUGE databases that map FQDNs to IP addresses. Not every DNS server knows the FQDN and IP address of every computer in the world; that's why there are lots of DNS servers all over the world, maintained by governments, universities, large corporations, etc. If a DNS server receives a query about a FQDN or IP address it doesn't know, it passes on that query to another DNS server (and perhaps another, and another...).
You can connect to any computer using either its FQDN or IP address. Don't believe me? Type 64.233.167.99 into your browser's location bar (instead of a FQDN), and see what happens (you then have to press Enter or click "Go").
Back to ContentsWhat does this have to do with making web sites?
A lot, really, because you can't just make up an IP address or FQDN for yourself or a client. The company that provides the internet connection (the ISP, Internet Service Provider) will assign an IP address. You can make up a domain name and use it, if it is not already in use. You may not have a choice about what comes to the left of the domain in your FQDN. You then have to register your domain with an Internet registrar.
You have to pay for this (duh). You (or your client) are paying for two things:
1) to register your domain so nobody else can use it, and
2) to add your information to their DNS server(s), otherwise no other computers will be able to contact yours.
You can register any domain name that is not already in use; you do not even have to use it for a real web site.
Many registrars also offer what's called domain forwarding, which means they will forward requests for your domain to some other address, as I described above. I own the domain name mward.ca; requests for that are forwarded to clubweb.interbaun.com/~mward, which you will see in your browser's address bar - not www.mward.ca.
The next section has more evil technical details - FTP and how to upload your web site.
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