TCP/IP

MicroCourse
Time
1 hour 51 minutes
Difficulty
Beginner
CEU/CPE
3

Video Description

TCP/IP Configuration (part 8) We continue our discussion of IP address by examining Dynamic IP addresses. Dynamic IP addresses are assigned by DHCP a service that determines and assigns all the administration and management of that IP address. After taking this lesson, you'll know what the DHCP Discover process is, when the communication with MAC address takes place, if it assigns the subnet mask, manages the subnetting process, Default Gateway, DNS, as well as all other information relative to this IP addressing life cycle. You'll also learn what the purpose of lease length is, examine what that process entails, how MAC address reservation works, and what the range entails for assigning Dynamic IP addresses.

Video Transcription

00:04
we talked about our static I p addresses. Now what's our dynamic I p address? Well, Adar dynamic I p address is when our computer gets an i p address through something called D h c p D h c P stands for dynamic host configuration protocol. It's essentially when our computer is getting all of that configuration information
00:22
for our I p address
00:24
default gateway subnet mask Indian s from somewhere else and maybe a d h c p server that we have set up with configurations on how to give us that information and maybe the router that we bought that has that set up. Or maybe the router that our Internet service provider gave to us that has all of that set up. So essentially, when we have our computer here
00:43
and our computer is
00:45
starting up, Windows is starting up, and we have our computer set up to automatically obtain I p address information.
00:52
Then it's going to use D H cp to do a couple of the following steps.
00:56
The first thing is going to do is is going to do what's called D H Cp Discover
01:02
D H cp. Discover simply means that our computer is going to send a broadcast message out on the network anywhere it can and in any direction that it can, Just saying,
01:11
Hey,
01:11
I need
01:14
a I P address. I need someone who can give me information on what I shouldn't eat. What I p address I should be What? Sub net mask I should be what I can use, what's in use on the network. What can I use?
01:26
So it sends out that D H cp Discover that says, Who can do this for me? The next step is it
01:32
received responses back. It's going to our computer is going to start talking with the first computer that responds back to it, or the first router that responds back to it and says, Oh, hey, I could do that for you.
01:47
So what now? Gets a response back? And during this entire thes couple steps before our computer gets an I P address, it's communicating with its Mac address when it's talking back and forth when our computer sends out a D H cp Discover, it says, Oh, hey, by the way, this is my Mac address. So when you're trying to talk back to me,
02:06
This is who I am. This is how you can find me
02:08
So it sends out its D H cp Discover in our home router.
02:13
Here's this Discover request and it says, Okay,
02:15
I could do that for you So it gives us a D H cp offer.
02:21
All right, our home Ratter
02:23
comes back
02:25
and it says,
02:27
Here's here's an I P. Address for you. We'll try this one on for size. Here's some information for you.
02:32
It sends an offer.
02:36
Now our computer
02:38
then takes this looks at it and it accepts the offer. Our computer sends back an acknowledgement of the H c p r.
02:46
Basically just an act what's called in a C K and act and acknowledge.
02:52
And it says, Okay,
02:53
cool. I'm good with this. Can I take? Can I use this? Is this still available? Now that I've seen this message and now that I'm okay with this, is this all good?
03:01
And then for the last time, our router will come back one more time and say, Yeah, this is still good. You can You can still use this. You're good to go
03:12
now. Our router or R D H C. P server, which everyone is using. We'll make it. We'll make a note in its in its registry, and it's it's TCP tables that this
03:23
computer is using this I p address. So you make a note of that.
03:28
So now whenever this anyone else asks for an I p address, it won't give that one out and will no long. It won't give that I p address out because it isn't no, it knows that it's being used.
03:38
And when anyone else on the network is trying to connect to this computer through the router, that router will automatically say, OK, I know who has this I p address. I know what Mac address is associated with this I p address. So I'm gonna go ahead and I'm going to send this information over to this person.
03:54
So that's what our D H CP process does. The HCP allows our computer to find an I P address,
04:02
but really it's more than just an I P address. The HDP gives us so many more options that we can configure. Besides just giving us an I P address, it also gives us our default gateway. We talked about a little bit before what? Our default gateway is essentially where we go next, our next step And it also tells us it can also give us our D. N s and
04:23
Formacion.
04:23
So give us our D. N s.
04:25
And it also tells us about routers that are in the area. Now, if
04:30
our d a. C P server isn't our router, we're not using our router for D H cp. This is important so that it tells our computer what a router is, which is also our default gateway. It also gives us information such as imaging computers so which computers can provide imaging information. Um, and then another thing that it gives us is it gives us a length
04:49
of a least length slash expiration.
04:54
Now, what is the lease? Well,
04:57
this is D H cp offer isn't good forever.
05:00
And for good reason. If this D H cp offer was good forever, eventually we would run out of I P addresses in certain situations. Say we have multiple friends that come in, vivid our house and asked for our wireless password, or we get new computers and get rid of old computers, and all of these have their own Mac addresses And because each Mac address could only have
05:19
one i p address associated with it.
05:21
Arkan are router will eventually say up no more.
05:25
I don't have any more I p addresses to give out all of these Mac addresses. Have all of these i p addresses and I don't have any more I p addresses in this network available to you. So we have a Lisa Lee. We have a least length and expiration. Where are router will say OK,
05:41
you can get a router R D A. C P server will say, OK,
05:46
you get this I p address. Here's all your information, but this is only good for
05:50
36 hours
05:53
and in about 24 hours from now, when 1/3 of your or when 1/3 of your lease is up, you need to come back to me and just reconfirm that you still want this and you're still good.
06:04
And if your computer does that, it retains his information and it restarts the lease. But if it doesn't do that before the 36 hours is up, then you're D H cp provider. Your D H P server or your router will now think. Okay, This computer hasn't come back to me within 36 hours. It hasn't said that it wants this lease still,
06:24
so I can give this to somebody else.
06:26
And if somebody else asks for not be addressed, it may give that out. That's why we have our police length slash expiration. When we purchase a router. A lot of times, our routers will come with the HCP enabled and D H cp already set up.
06:41
But
06:42
we can turn that on. We can turn that off. If we have a different GHT p server and we can set a couple of different, we can set a couple of different settings. So
06:50
one last quick look at this because we'll need to get rid of this to make some more space. But our D H cp. When our computer receives the HCP, it'll receive information such as our I P address. Our default gateway are D N s and our least length slash expiration.
07:08
Now there's something else we can do with our d A. C. P called ranges and reservations. We talked a little bit ago about our static I p addresses. Well, how does our d a c p server know about our static I p addresses? How does it not accidentally give that address out to somebody else? Say, if our partners turned off for a couple days,
07:26
how does it not say? Oh, your lease is up Even though we have, it's statically assigned. Well, we not only have two statically in from enter our information into our our
07:35
printer or our
07:38
file server or whichever we want our whichever computer, Whichever device we want tohave static I p address. We also have to set that as a reservation on our D h c P server on a router that does the HDP. This reservation is done by the Mac address. So again, par reservation is a setting that we can set on our D h C P server.
07:58
And this is done by
07:59
Mac address. So essentially, we go on our computer,
08:03
we find out we set all of our static I p address information,
08:05
we find out what our Mac addresses on our computer, and then we go to our d h C P server, and then we we essentially enter information into our d. C P server. This is Hey,
08:16
if you see any computer on the network with this Mac address? This is what its I p address is going to be. This is this is this Mac addresses I p address. Don't give this address out to anybody else because this computer is the only one who's allowed to use it. This is we need to reserve this for the printer. Another aspect of the HCP another configuration that we can change
08:35
is going to be
08:37
our range. R D C P range is essentially
08:41
what number of i p addresses will give out. So say we have
08:48
a internal private I p address of 1 92.1 68.1 dot one. Our network portion is 1 93 2.1 68 at one, and our host portion is the final octet, the 10.1 or the dot whichever, and we have one through 01 through 255 available.
09:07
But we don't want all of those available. We don't want all of those floating round to be given out by our d. A. C. P server. So we set that as just
09:15
13 50
09:16
r D c. P server can only give out that limited number of I P addresses. Maybe be for security reasons. We don't want all of these computers connecting to our network. We need it for bandwidth reasons. We don't want to 155 different computers connected to this one single router.
09:31
Sometimes people have multiple D H CP servers, where one B H C P server issues addresses for one certain range, and the other d. C P server will issue the rest of the addresses for a different range. They're different reasons why you may edit the range, but the pure and simple fact is
09:48
one of our configurations on our d. C. P server is something called Range so we can go on that D A. C P server. We can go on our router and tell it that within I basically say to our router, I know you have all of these addresses that you can use, but I just want you to use this segment when you give out addresses when you automatically assign I P addresses. In a nutshell is a wrap up.
10:09
Our dynamic I P addresses are typically going to be assigned by R D. A c P server
10:13
R D C P server can assign things such as our I, P address,
10:16
subnet, mask, D and S
10:20
and Gateway. It can also give us it. Also give us our least link and expiration. And on our d a c p server itself, we can set reservations by Computer Mac address and we can set ranges of how much of our available hosts ideas we want our d A C P service actually use.

Up Next

TCP/IP

The communication standard that devices use to exchange data across the internet

Instructed By

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Anthony Harris
Systems Analyst and Administrator at SAIC
Instructor