Network Terminology

A Mail Server is similar to a phone company’s “central office switch”.  In the case of Internet mail, there are numerous mail servers, DNS (Domain Naming Service) servers, and routers that allow you to easily exchange mail with other Internet users. A mail server consists of four parts.

• An incoming SMTP (Simple Mail Transfer Protocol) process, that accepts incoming SMTP connections (from mail clients or other mail servers) and puts the messages received into the message store
• An outgoing SMTP process that relays received mail addressed to accounts on other mail servers
• A POP process that allows a mail client program to retrieve messages from the message store
• A message store that is used to temporarily store messages received from the incoming SMTP process, before they are retrieved (at the request of a mail client) by the POP process

Relevance:  A mail server is important because it can store messages and forward messages for you.  You can also send mail to a large group of people at once.  For example, if I need to send an e-mail to every teacher at my school, I send it through a mail list instead of each individual teacher.
 

A Web Server is located on a local area network (LAN), with the LAN connected via a router to an Internet access provider.  The Internet access provider has a direct connection to a network node on the Internet. A full T3 or switched multimegabit data service (SMDS) connection is usually used to provide Internet access for a large group of organizations.  See the flow chart below.

MX (Mail Exchange) records point to the mail exchanges for one host.  DNS is structured so that you can actually specify several mail exchanges for one host.  This provides a greater probability that e-mail will arrive at its intended destination.  The mail exchanges are listed in order in the record, with a priority code that tells the order in which the mail exchange should be accessed by other mail delivery systems.  If first priority doesn’t respond in a given amount of time, the mail delivery system tries the second one, and so on.  A mail exchanger is another name for an SMTP mail server. So, MX records tell where to deliver the e-mail for your domains.  It is similar to the current phone system where we have country codes, area codes, prefixes, and an actual four digit phone number.

Relevance:  MX Servers are important so your e-mail is actually sent, sent to the correct place, and received.
 

IP Addresses are numeric addresses given to servers and users connected to the Internet.  An IP address is an identifier for a computer or device on a TCP/IP network. An IP address is most often expressed as a 32-bit numeric address written as four numbers separated by periods. Each number can be zero to 255.

IP addresses keep all of the computers straight.  Each machine is assigned a unique address. An example of an IP address is 214.176.15.84.  Every machine on the internet has a different IP address.  When you dial from a modem, your machine has a unique IP address, but it may be different the next time you dial in.

To find the current IP address of your Windows machine type the command WINIPCFG.EXE.  To see step by step instructions, click here.

As far as Internet’s machines are concerned, an IP address is all you need to talk to a server.  For example, if you type the URL http://128.174.90.12, you will arrive at the LRS Server.

Relevance: It is important so you can contact a server or an individual computer.  For example, my class can “call” another class via the computer if we know the other class’ IP address.  I can also contact U of I’s education server by typing in their IP address.

Some type of technical failure is inevitable resulting in a system crash.  It is likely your system will eventually go down.  In the process, you could lose the data your users store on your systems.  You can protect yourself by backing up your critical data.  Offline backup strategies are most commonly used.  It involves copying data onto small removable media often using compression techniques.  The most commonly used offline media is magnetic tape. Tape Backup is fairly inexpensive and simple to utilize but tends to be fairly slow.  Magnetic tape can be unreliable and requires careful handling and storage. It is still used often because the benefits outweigh the risk of losing important information.

Relevance:  It is crucial to have a tape backup of any important data. If your server or computer crashes, more than likely you will lose all of your data.  A tape backup of all critical data will ensure the ability to restore lost data.
 

10 MBPS  and 100 MBPS Connection refer to the speed with which data can be transmitted from one device to another.  Data rates are often measured in megabits (million bits) or megabytes (million bytes) per second.  The following table shows these speeds along with the carrier technology, the physical medium the data is traveling on, and the application.
 

Carrier Technology	Speed	Physical Medium	Application
Ethernet	10 Mbps	10BASE-T (twisted pair)' 10 BASE-2 or 5 (coaxial cable) 10BASE-F (optical fiber)	Most popular  business local area  network (LAN)
Fast Ethernet	100 Mbps	100BASE-T4 (twisted pair); 100Base-TX (twisted pair)' 100BASE-FX (optical fiber)	Workstations with  10 Mbps Ethernet cards can plug into a Fast Ethernet LAN
FDDI	100 Mbps	Optical fiber	Large, wide range LAN usually in a large  company or a larger ISP