VPSit - Hosting 101

Let's first start off by saying that nothing is magic and it does not "just" happen. From the time an individual types something into a web browser to the time the information is loaded onto a web browser there are many different technologies and services that are used. We will explain the basics of some of them there. By no means is this guide supposed to teach everything about these technologies (hence it is only a level 100 class), but it will be a good guide for most users to get started with.

What is a client?

Technically this is a computer system that accesses one or many remote systems on a network. But to keep things simple let's just say that this is the system / user that is making the request. For instance if you type http://www.example.com in your web browser then you (actually your web browser) is the client. You are requesting for some information / service on a remote computer (actually a server). You might not have realized it but you have been a client for years.

What is a server?

This is the remote system that the client connects to request the information. This remote server will then return the information that the client asked for, in a format that the client can understand. This data / information is then viewed by the user that requested the information.

What is a URL (Uniform Resource Locator)?

In an attempt to keep things very simple here think of it as nothing more than a web address prepended by the protocol (and sometimes extra information). Here is one basic example and one advanced example.

Basic example of a URL:

http://www.example.com/

Protocol (http): This refers to the protocol that the the request (from the client looking for. HTTP is the Hyper Text Transfer Protocol and is used to see web sites. HTTPS (Hyper Text Transfer Protocol Secure) is also used to view web sites but uses encryption to keep the data that is submitted private.

Fully Qualified Domain Name (FQDN) / Domain Name (www.example.com) : This is the name of the system / server that you want to connect to.

Advanced example URL:

http://user:pass@www.example.com:80/pages/prices?cat=office#chairs

Login (user:pass@): If information is protected and requires a username and a password it can be specified in this format. The username and the password are separated by a colon.

Fully Qualified Domain Name (FQDN) / Domain Name (www.example.com) : This is the name of the system / server that you want to connect to.

Port (80) : When a client connects to a server is connects to a specific address on a server call a port. For instance if you entered an office building you would go to an individual office or suite number. Accounting department might be office #100 and the human resource department might be office #200. The same thing happens here for the protocol you are using.
A server may have a web server and a mail server running on it, so it uses the incoming port number to know what the client is asking for. The port is not needed to be entered unless it is not the standard / default port for that protocol. HTTP for instance uses port 80 and HTTPS uses port 443.

Path (pages/prices) : If a particular piece of information is requested for on the server then it is given as the "path". If this is not included then the server will generally return the default page for that resource.

Query (cat=office) : If specific parameters are needed to be given then this will be passed to the server. Generally this is only done if the server has the ability to understand these parameters that were given and analyze them and use them some way. If you were to enter your name in a web form then this would be a good example of sending a query string to the the server. "?firstname=john&lastname=smith" would be an example of passing two values to the server.

Anchor (chairs) : If you wanted to go straight to a particular part in the page then an anchor is used. This helps the client go directly to the information that they are looking for instead of scrolling through all of the information on the screen to find what they are looking for.

What is DNS?

The domain name system / service (DNS) is the technology used to find servers and clients. Computers do not have names by default. They have telephone number called IPs (Internet Protocol). Just as you might have a telephone number for your local police office so does the web site. You can think of DNS as being the "voice activated dialing" of the Internet. It will automatically find the computers telephone number for you. You don't even have to break our your telephone book! It will take care of everything for you.

DNS handles the mapping between host names, which we humans find convenient (example: www.DNSMadeEasy.com), and Internet addresses which computers deal with (192.168.98.2).

What is name server?

The name server is the server that will do the conversion of the fully qualified domain name to the IP address. There are generally two types of name servers. There are resolving name servers and authoritative name servers. When you are hosting a web site or offering hosting services you generally only need to be concerned with the authoritative name server, but it is important to understand both and how they are used.

When you type your URL into your web browser the web browser turns into a client but needs to find the IP of the web server. Your web browser will ask it's resolving name server to get the IP address for the server in question. The resolving name server can be entered into your network properties manually but it is most often assigned to you automatically when you connect to your ISP. Your ISP is your Internet Service Provider and is how you connect to the Internet. This resolving name server is the worker and asks multiple authoritative name servers where the IP address is for the server in question. Once it finds this information then the resolving name server will return this IP to the web browser (the client).

The authoritative name servers are phone books of the Internet. There are millions of these authoritative name servers out there and they are all important for a specific group of domain names. When you are doing web hosting you need to properly configure an authoritative name server to answer for your domain name. If this is not setup then the resolving name servers will never be able to find this information correctly.

What is web server?

This is the computer system that will respond with the information that the web client (the web browser such as Internet Explorer or Firefox) is asking for. It will give the information to the web client in a format that the web client can understand. This web client will then present this data to the user so he / she can read it.

What is an email / SMTP server?

Email works over the SMTP protocol (Simple Mail Transfer Protocol). This is sort of server deals with the handling of these emails from one server to another. An SMTP server can accept an email, receive an email, or can do both. SMTP's default port is 25.

What is a POP / IMAP server?

POP (Post Office Protocol) is one of the protocols uses to read stored messages from a server. POP is a client/server protocol in which e-mail is received and held for you by your Internet server. Periodically, you (or your client e-mail receiver) check your mailbox on the server and download any mail. Example POP clients would Outlook, Outlook Express, Thunderbird, Eudora, etc.. POP3 (Post Office Protocol 3) is the most recent version of a POP.

Internet Message Access Protocol (IMAP) is another standard protocol for accessing e-mail from your local server. IMAP (the latest version is IMAP4) is a client/server protocol in which e-mail is received and held for you by your Internet server. You (or your e-mail client) can view just the heading and the sender of the letter and then decide whether to download the mail. You can also create and manipulate folders or mailboxes on the server, delete messages, or search for certain parts or an entire note. IMAP requires continual access to the server during the time that you are working with your mail.

POP is generally used to just download the messages from the server to the client where as IMAP is generally used for constant updating from client to server.

What is an FTP server?

The File Transfer Protocol (FTP) is used to transfer files from client to server. This is used as a quick way to transfer a file from one computer to another. Generally this is used for larger files or is used if you want to give multiple users the ability to receive a file (without emailing it to each person).

What is a registrar?

Where you need to go to buy a domain name you buy a domain name from a registrar. This company is responsible for checking to make sure that your domain name is available and then making sure that you in fact do get that the domain name that you are asking for (if it is available). When you register a domain with a registrar you need to tell the registrar the authoritative name servers that you want to use for your domain name.

What is a web based control panel (WBCP)?

As you can see from above there are many different technologies that go into hosting. We covered the very basics of each of these servers and barely touched the surface of any of these. To offer web hosting to a customer or to even offer web hosting for yourself you need to be able to configure the software on the servers for everything to work together smoothly. Individuals go to school for years to become experts in just one of these server technologies. On top of that there are many different software choices once can choose from when you offer hosting. A web based control panel is an interface designed to keep a lot of the complexities away from the end user.

Some of the more popular WBCPs are Plesk (what VPSit uses), CPanel, DirectAdmin, Helm, H-shere, Ensim and Sphere.

Putting it all together. What happens when you type a URL (Uniform Resource Locator) into your web browser?

As soon as the web browser is told to get information it becomes a web client and starts looking for some information. Make sure you read all of the information in this class and let's step through each step one by one.

You enter a URL in your web browser.
The web browser breaks down the URL to find the server that it needs to contact (this is the FQDN of the URL).
Your web browser becomes a client in DNS to find the IP address. It asks the resolving name server that it is given for the IP address.
If your resolving name server knows the IP then it just returns it to the web browser. Otherwise, it goes through a series of steps and asks a bunch of authoritative name servers what the IP is. Either way it will eventually tell the web browser the IP or it will eventually say that it could not find the IP.
The web browser now acts as a client to the web server and passes the full URL to the web server.
The web server will then return the requested information back to the web browser (the web client).

Would you like to see more information in our guide? Please let us know.
E-mail: webmaster@vpsit.com