Special Purpose IP Addresses

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Time
8 hours 19 minutes
Difficulty
Beginner
CEU/CPE
8
Video Transcription
00:00
So now that we've covered some of the basics of I p address ng, the next thing I want to talk about is the specific I P addresses that are set apart for particular use.
00:10
The first set of I P addresses that we'll talk about is one called RFC 1918,
00:16
if you'll remember from earlier, our FCS contain the rules and the specifics of the TCP I P Protocol.
00:23
So what's been amended to the protocol throughout the years? It's just going back.
00:30
So what's been amended to the protocol throughout the years is a specific set of I P addresses that are determined to be just for internal use,
00:38
meaning that if these addresses appear out on the Internet, the Internet routers should drop packets.
00:44
So all my internal network, I will almost always see an I P address on the 10 network
00:50
or the 172.16 network through the 172.31 network
00:56
or something on the 192168 network.
00:59
Again, those are reserved just for internal devices.
01:03
The second bullet must be a behind a nat device,
01:07
not stands for a network address. Translation.
01:11
If we have these private addresses that can't go out on the Internet.
01:15
That's a problem because my hosts need to go out on the Internet. And that's okay
01:19
because we have network address translation, which essentially hides our internal i p address ng and allows R I P addresses that are going out to the Internet to present with a different source. Address a public source address that's been received from our Internet service provider.
01:34
We'll talk about that leader, but I just want you to know if you're thinking about how can I get on the Internet,
01:40
all that is resolved.
01:41
This is behind a router, and it's a security benefit that you have a sense of internal I P addresses that can't be routed on the Internet.
01:51
There's also a loop back address, which is 1 27.0 point 0.1,
01:57
ultimately sometimes refer to it as home because we mean my computer.
02:02
So when I paying 1 27 001 that's really testing my network card to make sure that it can send and receive data
02:10
every now and then you have that issue that you just can't figure out
02:15
it never hurts to make sure that your N I C is sending and receiving properly
02:20
a p i p a. Addresses
02:22
automatic i p addressing is what a p i p a stands for
02:27
when were configured to get an IP address from a D H. C P server.
02:30
We talked about this in Chapter one.
02:34
Client comes online and send out a Discover message that says, Hey, is anybody out there on the D. H C P server?
02:39
So the D. H. C P series are going to offer an I P address.
02:45
We're going to respond and acknowledge that the whole door a phase we discussed with the D H C P section.
02:50
But what if the client sends out the broadcast that says, Hey, is anybody a D h c p server?
02:55
And nobody answers?
02:58
What if there is no D h C P server available?
03:00
That's okay, because the client will auto configure an I P address, beginning with 169 to 54 something something
03:09
that is much better than the way it used to be
03:12
back in the early Windows 98 days. If a client couldn't get an I P address from a D. H C P server. The address it would have to be would be 0.0 point 0.0, and you can't do anything on the network with that type of address.
03:25
At least now. Clients AUTO CONFIGURE with this 169254 address
03:30
If the D. H C P server is down for everybody, we can at least have some local communication.
03:36
So that's a good step in the right direction, and that's referred to as a P I. P a address.
03:45
We've already talked about the network ID, and we said the network idea is an I P address, with the full host portion also to zero.
03:52
We've also said we don't assign that network ID to any particular device,
03:57
but we do use it to summer as the network.
04:00
We might use it on access control lists on Browder's to describe a pathway to a certain route.
04:04
We might use it on firewalls to say, block all traffic to particular network,
04:09
but it does not go to a specific device.
04:12
It's there to summarize.
04:15
We also have unit casting, multicasting and broadcasting.
04:19
Unit casting is what we see the most,
04:21
and that's from a single host going out to a 1 to 1 communication.
04:27
In this illustration, I'm going from 17 to 16.4 point 1 to 172.16 point 4 to 53
04:36
That's a 1 to 1 communication, and that's unit casting.
04:42
Mhm.
04:43
If we have something like a video conference that certain hosts are participating in,
04:46
or if we're sending out an image of a Windows system, only the Windows devices
04:51
might use a multicast.
04:54
Essentially, the clients will have to have special software to log in to get their most I cast going back.
05:00
Essentially, the clients will have to have special software to log in to get their multicast address and subscribe to this group.
05:08
But it is a way we can send them the same message or data to multiple computers.
05:14
Broadcasting goes to every host on the subject,
05:15
so the broadcast address is going to be the network ID plus the host portion also to binary ones.
05:23
In this case, if you look at the diagram on the left, you see a broadcast from the source to the destination.
05:30
What I would assume by looking at this is they're using a 24 bit subnet mask and not using the standard Class P address.
05:38
172.16 point 4 to 55
05:42
The 255 indicates all hosts on the sub net, so the broadcast addresses. When all hosts are said to binary ones,
05:48
remember that your I P address as a client can't have. The host is all binary zeros are all binary ones.
05:56
Those are addresses that are reserved,
06:00
special I p addresses
06:02
What I want you to take away from. This is the 1918 private internal addresses the 10 network
06:09
172.16 to 172.31 and 192.1 68.
06:15
The loop back address. The entire range of 1 27 is reserved for troubleshooting going back.
06:24
The loop back address. The entire range of 1 27 is reserved for troubleshooting, but specifically, the loop back is often used as 1 27.0 point 0.1,
06:35
and it's to test out your network.
06:38
We have network IEDs, which are used to identify the network for routers, firewalls and whatever purpose we need to summarize the network.
06:46
We then talked about a P I. P a. Addresses
06:49
any time on the test that you see a host with a 169.254 address,
06:55
you know that it's trying to get an I P address from D H C P.
06:59
But D H C P is not available.
07:01
That very well may be the problem in question. They're asking you to troubleshoot.
07:06
And finally we have, you know, cast one on one communication,
07:11
multi tasked one of many
07:13
and broadcast one to all.
07:15
Remember, the broadcast address is going to be the network ID plus all the host bits set to binary ones.
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