CompTIA Network+ (2009 Objectives) Tutorials
Protocols / Understanding Mail Protocols
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Subtitles of the Movie (CompTIA Network+ (2009 Objectives) / Protocols / Understanding Mail Protocols)
Email is one of the predominant Internet applications that runs in the TCP/IP Suite and there are three Protocols involved in moving the mail around that you're going to see on the Network+ exam and you need to be aware of. And let's back up here just a second and talk about the two basic functionalities that we're looking for in mail, and that is, I need some way to send the mail out and then I need some way to receive mail. And there are protocols that are designed, included in the TCP/IP Suite to provide this functionality. Now to send the mail we're always going to us SMTP, talk more about that in just a second here. To receive the mail we're going to use one of two Protocols, either IMAP, and it's actually IMAP 4 now, or POP 3. Now let's dig into each one of these just a little bit. First of all, when we're sending mail on the Internet using TCP/IP, we are going to employ the SMTP Protocol. Now that stands for Simple Mail Transfer Protocol. This is responsible for sending mail messages to mail servers. Now the bottom line is, 99.9 percent of the time, when mail is moving between mail servers out there on the Net it is using SMTP to move that message around. Now generally SMTP is a sending protocol, it sends mail out. It sends the data in plain text. Now understand, there was nothing built into the Mail Protocols that provides us any kind of security or anything like that, and as a matter of fact, when you use Tools like Outlook and those kinds of things, whatever you're using, the Entourage on the MAC side, these things are really doing nothing more than packaging up our messages and sending these EHLO Commands and so forth in the SMTP Protocol. And so you can, you can masquerade as anybody you want to, you can do all kind of wild stuff with it, and again, that's something else that's kind of interesting. Just go out and do some searching on that stuff and you can see some cool stuff, but anyway, SMTP sends the mail and it uses, by default, Port 25. So when you see Port 25, SMTP, that's mail that's being sent. Now there's actually an updated version of SMT called ESMTP, or Extended SMTP, and it's a just newer, shinier version. It has a few more Commands and it's what most people are using now. However, this is one of these oddities in IT, we still refer to it as SMTP. It's very, very rare that you're ever going to hear an administrator, or even a mail administrator, respond to this Protocol, or refer to it as ESMTP. Most just simply still call it SMTP. Now on the receiving side, when we get ready to receive the mail, there's really a couple of ways to do it. The POP 3 Protocol, which is the Post Office Protocol, and the three simply means we're on version 3 now, is one of the ways we get mail, and IMAP or the Internet Message Access Protocol is another way that we get mail. Now let me say something here. These are the ways that we retrieve mail off a mail server. And so the POP 3 will go up there and grab it, and we refer to that as popping a mailbox. The mailbox has mail in it, we use POP 3 to reach up there, and just kind of see yourself like a balloon sticking a pin in, it pops the balloon, all the mail falls out. Now IMAP is really just kind of an enhanced version of Post Office Protocol or POP 3, but IMAP gave us the ability to do some other cool things with mail. Some of the functions that you see like bolding, changing colors, and so forth, some of that's coming from IMAP, and the real truth is that we're actually using IMAP 4 now. But IMAP is the Protocol that you're going to see listed on your Exam. Now both of these, or either of these, I should say, will pull messages from a remote mail server and that is exactly what these programs, like Outlook and Entourage, and all these things do. POP 3 uses Port 110, IMAP uses Port 143, and you will see these when you set up an account in Outlook if you've ever done that. You can change these ports, you can look on other ports, you can do all kind of cool things. And you can set up encryption on your mail, and that will change your port numbers to 843 or 943 something like that. I'm going blank because it's live, but those are the three Mail Protocols you need to be aware of on this exam. SMTP sends mail out, POP 3 and IMAP, and you could see IMAP 4, for the purposes of this exam, it's the same thing, POP 3 and IMAP receive mail. They're responsible for pulling the mail off the Web server when it's ready to be delivered. So that's the three Mail Protocols you need to be familiar with and the port numbers on the Network+ Exam.
Tutorial Information
| Course: | CompTIA Network+ (2009 Objectives) |
| Author: | Mark Long |
| SKU: | 34216 |
| ISBN: | 1-936334-90-9 |
| Release Date: | 2011-04-29 |
| Duration: | 6 hrs / 91 lessons |
| Work Files: |
Yes |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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