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.
The first set of I P addresses that we'll talk about is one called RFC 1918,
if you'll remember from earlier, our FCS contain the rules and the specifics of the TCP I P Protocol.
So what's been amended to the protocol throughout the years? It's just going back.
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,
meaning that if these addresses appear out on the Internet, the Internet routers should drop packets.
So all my internal network, I will almost always see an I P address on the 10 network
or the 172.16 network through the 172.31 network
or something on the 192168 network.
Again, those are reserved just for internal devices.
The second bullet must be a behind a nat device,
not stands for a network address. Translation.
If we have these private addresses that can't go out on the Internet.
That's a problem because my hosts need to go out on the Internet. And that's okay
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.
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,
all that is resolved.
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.
There's also a loop back address, which is 1 27.0 point 0.1,
ultimately sometimes refer to it as home because we mean my computer.
So when I paying 1 27 001 that's really testing my network card to make sure that it can send and receive data
every now and then you have that issue that you just can't figure out
it never hurts to make sure that your N I C is sending and receiving properly
a p i p a. Addresses
automatic i p addressing is what a p i p a stands for
when were configured to get an IP address from a D H. C P server.
We talked about this in Chapter one.
Client comes online and send out a Discover message that says, Hey, is anybody out there on the D. H C P server?
So the D. H. C P series are going to offer an I P address.
We're going to respond and acknowledge that the whole door a phase we discussed with the D H C P section.
But what if the client sends out the broadcast that says, Hey, is anybody a D h c p server?
What if there is no D h C P server available?
That's okay, because the client will auto configure an I P address, beginning with 169 to 54 something something
that is much better than the way it used to be
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.
At least now. Clients AUTO CONFIGURE with this 169254 address
If the D. H C P server is down for everybody, we can at least have some local communication.
So that's a good step in the right direction, and that's referred to as a P I. P a address.
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.
We've also said we don't assign that network ID to any particular device,
but we do use it to summer as the network.
We might use it on access control lists on Browder's to describe a pathway to a certain route.
We might use it on firewalls to say, block all traffic to particular network,
but it does not go to a specific device.
It's there to summarize.
We also have unit casting, multicasting and broadcasting.
Unit casting is what we see the most,
and that's from a single host going out to a 1 to 1 communication.
In this illustration, I'm going from 17 to 16.4 point 1 to 172.16 point 4 to 53
That's a 1 to 1 communication, and that's unit casting.
If we have something like a video conference that certain hosts are participating in,
or if we're sending out an image of a Windows system, only the Windows devices
might use a multicast.
Essentially, the clients will have to have special software to log in to get their most I cast going back.
Essentially, the clients will have to have special software to log in to get their multicast address and subscribe to this group.
But it is a way we can send them the same message or data to multiple computers.
Broadcasting goes to every host on the subject,
so the broadcast address is going to be the network ID plus the host portion also to binary ones.
In this case, if you look at the diagram on the left, you see a broadcast from the source to the destination.
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.
172.16 point 4 to 55
The 255 indicates all hosts on the sub net, so the broadcast addresses. When all hosts are said to binary ones,
remember that your I P address as a client can't have. The host is all binary zeros are all binary ones.
Those are addresses that are reserved,
special I p addresses
What I want you to take away from. This is the 1918 private internal addresses the 10 network
172.16 to 172.31 and 192.1 68.
The loop back address. The entire range of 1 27 is reserved for troubleshooting going back.
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,
and it's to test out your network.
We have network IEDs, which are used to identify the network for routers, firewalls and whatever purpose we need to summarize the network.
We then talked about a P I. P a. Addresses
any time on the test that you see a host with a 169.254 address,
you know that it's trying to get an I P address from D H C P.
But D H C P is not available.
That very well may be the problem in question. They're asking you to troubleshoot.
And finally we have, you know, cast one on one communication,
multi tasked one of many
and broadcast one to all.
Remember, the broadcast address is going to be the network ID plus all the host bits set to binary ones.