Class C addresses start with binary 110.
So once again, this is not 110 in decimal, but 110 in binary.
The zero in this case is in the third but position in the first octet.
So Class A had zero in the first but position Class B in the second, and now Class C has the zero in
the third.
But position going through the combinations in the first octet will give us a range of 192 to 2 to three.
So this is the range of class C addresses.
In Class C addresses.
The first 24 bits is network, the last eight bits is host.
So for an address of 192.1681.1, we know that this is a class C address because the first octet is
in the range 1922223.
So we have a class C address, which means that the first 24 bits is network and the last eight bits
or octet is the host portion of the address.
So in other words, just by looking at an address, you'll now be able to determine if it's class A,
Class B and Class C based on the ranges we've now discussed.
You'll also be able to know which portion is network and which portion is host.
But be careful.
As mentioned, these classes have been superseded by CIDR or C IDR.
Now Class D addresses are different to Class A, B and C, class A, B and C are used for unicast traffic.
Class D addresses are used for multicast traffic.
Now, with multicast addresses in the first octet, the zero is in the fourth position.
So in these addresses, the first three binary bits are set to one, followed by a binary zero.
Going through all the combinations, the range is from two to 4 to 239 in the first octet.
So this is the range of multicast addresses in IP version four.
So as an example, address to 39.1, 1.1 is a private multicast address which could be used internally
within your organization.
Other examples of multicast addresses include well known multicast addresses for routing protocols such
as OSPF.
The OSPF routing protocol uses multi costs 224.0.0.5 and 224.0.0.6.
These multi costs in the 2 to 4 range are known as link local multi costs, as these multi costs do
not propagate off the local link or local segment.
And multi costs in this range are often used by running protocols such as OSPF, RDP and others.
A multicast implies once again that one device is talking to a group of devices rather than 1 to 1 communication
class.
E addresses are reserved addresses.
They start with four binary ones and on the range two 40.02020 all the way to 255 to 50 5 to 50 5 to
55, which is a reserved address for broadcasts.
We'll talk about broadcasts in a moment.
But once again, the important piece to understand here is that Class E addresses on the range 240 to
255 in the first octet class E addresses are reserved addresses for both testing and other purposes.
So a Class A address uses the first eight bits as the network portion.
So in a pure class address, the first eight bits are network.
So in this example, we've got network ten 0.0.0.
So that's the network address and we have an IP address of 10.1 or 2.3, which is the address configured
on a host.
So this is the host portion of the address and this is the network portion of the address.
Class E networks are once again in the range 1 to 126 in the first octet.
So if a router such as the one in this picture receives traffic going to an IP address of ten .1.1.1,
the router would know that the host is on Network ten because this is a Class A network.
So in this case, it would route the traffic to the left hand side in the same way if it receives traffic
going to an address of 12.1, point one, point one.
It knows that the host is on Network 12 and it would therefore route the traffic to the right hand side.
This is the reason why two hosts can have the same host portion.
So in this.
Example, the host portion is 1.1.1 because they are on different networks.
The network portion is different.
The Rada can use the clause full network.
In other words, the first octet consisting of ten or 12 to differentiate between multiple networks.
So in this case, it's routing on the first eight bits of the address with Class B networks.
The first eight bits denotes the network portion of the address.
So in this example, one 7 to 16 is the network portion.
So this is the network address and a host may have an address such as 172 16 one or two.
So one or two is the host portion of the address.
Class B networks are in the range 128 to 191 in the first octet.
So in the same way as the previous example, a router can route traffic to an address of 172. 16 1.1
because it knows that the network is 172. 16 and it can therefore route the traffic to the left hand
side traffic going to host one 7 to 17 .1.1 is routed to the right hand side because the network portion
is one 7 to 17, whereas this host with IP address one 72.69 1.1 has the network portion of one 72.16
routers can route correctly once again, even though the host portion is the same.
In other words, in this example it's 1.1, but in this case the network portion is different.
So routing takes place correctly.
The router knows that these two hosts are on separate networks because the network portion is different
and in close see addresses 1921681.0 would be a network address.
A host address would be something like 192.168.1.1 close see addresses on the range 190 22223 in the
first octet.
So once again, there are two devices in this example and they have the same host portion, in other
words, dot one.
But the network portion of these two host addresses is different.
On the left hand side, we have 192.168.1.
And on the right hand side we have 192.168.2 in class C addresses.
The first 24 bits or the first three octets of an address denotes network and the lost octet or lost
eight bits denotes host portion in a class C network.