So once again or if C 1918 discusses IP addresses that are not readable on the internet, they are three
blocks of addresses, one class A network, 16 Class B networks and 256 Class C Networks.
Here are the range of addresses once again.
And remember when you are sending traffic internally from an IP address such as 10.1 1.1 to a website
such as google.com or Facebook.com, your IP address has to be netted or network address translated
to a public IP address such as 15.1 1.1.
This is a public class A address, and this is a private class A address.
These addresses will not be accepted by Internet service providers and therefore will not be routed
onto the Internet unless, of course, an Internet service provider forgot to add an access list.
Blocking traffic from these networks.
So in this example, my PC has an IP address of 10.0 0.6.
That is a private IP address, which is not readable on the Internet.
But I am able to ping yahoo.com, which has a public IP address of 87.2, 48.1, 22.1 22.
And that's because my IP address is being netted or network address translated by my router when I send
traffic to the internet.
Here's another example.
Ping Google.com.
The pings succeed because once again my IP address is being netted.
Nat is not covered in this video.
Please refer to other videos for explanations of network address translation.
But in brief, Nat will translate one of these IP addresses to a publicly readable address when traversing
a router.
That's how I'm able to use a private IP address on my local PC, but still be able to access devices
on the internet.
My address is being noted when I traverse my local internet gateway, which could be as simple as your
router at home, which connects you to the internet.
The next special IP address range is the IP version for link local addresses or more formally dynamic
configuration of IP version for link local addresses as per or FC 3927.
Microsoft referred to this address order configuration method as automatic private IP address or API
pay.
So that's Microsoft IP version for link local addresses.
Now this is used where a PC is configured for DHCP or dynamic host configuration protocol, but no DHCP
servers are available.
So an IP address cannot be allocated via DHCP and therefore the PC automatically chooses an IP address
in the range.
169.254.0.0.
This allows computers to use link local IP addresses for communication on a local segment.
Now, in the really, really old days of networking, going back to Windows 3.1, if you wanted to PCs
to communicate, you had to either allocate an address using DHCP or you had to manually configure the
IP addresses on the PCs to communicate with each other.
These days, that's not necessary because IP version four Link local addresses will allow two computers
to communicate with each other when no DHCP server is available.
So if you connected to PCs back to back using a cable, they'd be able to communicate with each other
without the user having to configure static IP addresses on those devices.
The PCs would simply use an IP address in this range and be able to communicate with each other.
Hosts randomly generate the host specific portion of the address.
This is a class B address.
Notice the mosque 255.255.0.0, which indicates that the first two octets is a network and hosts will
randomly choose the host specific portion of the address.
Once again, this makes the lives of non-technical users a lot easier because they can simply connect
two devices together without the need of a DHCP server allocating addresses.
The two PCs can immediately communicate with one another.
The user doesn't have to configure a DHCP server or manually configure IP addresses on the PCs as long
as the two PCs are connected via a cable or a local segment through a switch.
As an example, they can communicate using IP.
So a PC with IP address 16922541.1 can communicate with another PC which for example, chose an IP address
of 1692541.2.
No manual configuration is required.
In this example, I'm using consecutive addresses, but typically the addresses chosen by the hosts
are random and won't be sequential.
Like in this example.
Be careful.
However, with this address range it's non readable.
In other words, the hosts can communicate on the local link, but their traffic is non ratable.
This can cause issues because users will be able to communicate with other devices on the local segment
or local link, but they will not be able to communicate with the devices on the internet or devices
in a different subnet.
So if you type IP config on a PC, for example, and you see that the PC has an address in the range
160 9.254.6. x.
That means the PC was not able to get an IP address via DHCP and dynamically allocated itself an IP
version for link local address.
No DHCP server was available and thus an IP address wasn't allocated to the device.
It simply chose an address from the one 6925 for address range.