What I'd like to point out once again is that each website is resolved to a different IP address.
Lastly, if I ping CNN.com, notice that that also resolves to an IP address, but it's different to
the previous examples.
DNS is doing the name resolution, so it's resolving a domain name to an IP address.
And that's how I'm learning the IP address of CNN.com or Google.com.
You can ping many of the well known websites on the Internet to find out what the IP addresses are.
You could also use GNSS lookup, which just does a DNS resolution of a domain name rather than trying
to ping the server.
So in summary, the devices on the Internet have been configured with IP version for addresses.
I'll explain more about the formatting of IP addresses in the next few minutes.
But for now, just take note that every device has an IP address and that includes my own machine.
The command IP config will show me the IP address on my local machine when using windows.
So in this example, my IP version for address is ten .0.0.6.
You'll also notice here that I have an IP version six address of 2001.
Colon 20.
Colon Colon two.
In this video, we concentrating on IP version four addresses, but in another video, I'll explain
IP version six.
IP version six is becoming more and more important because IP addresses are now exhausted in certain
parts of the world.
IP version four or Internet protocol version four is a layer three or network layer protocol as per
the OCI model.
In a different video I explained the OCI model.
So if you're not sure about layers, please refer to that video.
IP version four is a connection less protocol.
In other words, there are no sessions formed.
When traffic is transmitted, the transmitter simply sends data without notification to the receiver.
No status information is sent back from the receiver to the transmitter.
It's totally connection.
Less TCP IP or transmission control protocol, on the other hand is connection orientated.
TCP will set up a session, so before transmission takes place in TCP IP, the transmitter sends what's
called a sun or synchronization message to the receiver.
There's a sun ack message from the receiver to the transmitter and then a ack or acknowledgement message
from the transmitter to the receiver.
So before any data is transmitted, but devices using TCP go through what's called the three way handshake
syn sent EC and ACH.
IP, on the other hand, doesn't do any of that.
Each packet is treated independently of other packets.
That's why traffic can take different paths to get to a destination.
Routers will route the traffic via different paths based on options such as load balancing.
Because each packet is independent and IP is a connection less protocol routers can also base routing
decisions on different values, such as bandwidth or hop count, but it is possible that packets from
one session take divergent or different paths to get to a destination.
So for example, RIP will base its routing decisions on hop count, which is not good, and hence REP
is not used that often anymore.
OSPF will base it on bandwidth.
Other routing protocols will use their own metrics to determine the best path.
I'll be discussing routing protocols in more detail later in this course, but in brief, routing protocols
determine the best path or best route from A to B.
This is based on the hierarchical addressing structure in IP version four and IP version six, where
we have both a network and host portion as part of the address.
Routers based their routing decisions on the network portion of the address rather than on the host
portion of the address.
And I'll explain network and host portions in a moment.
IP also only gives best effort delivery of packets.
There is no guarantee of packet delivery.
Any packet could be misdirected, it could be duplicated, or it could be lost in transmission when
sent to a destination.
And that should be expected in IP transmissions.
Once again, TCP, which is a connection orientated protocol, has the ability to retransmit packets
that go missing.
UDP Another layer for protocol doesn't retransmit packets if they get dropped.
Simply lost and the applications need to take care of that.
There is also no data recovery features in IP.
If the packet, for example, gets corrupted, the end devices need to handle that and not the routers
in between.
So in summary, IP has no built in sessions, no data recovery, no transmissions.
Higher layer protocols such as TCP IP will need to handle dropped packets, corrupted packets, misdirected
packets and so forth.
IP does not provide those features and relies on higher layer protocols to implement those features.
So let's look at the format of an IP version for address.
An IP version for address is 32 bits in size, normally written in dotted decimal notation such as this
example 10.1 1.1.
Each of value such as ten is eight bits in size.
So in other words, we have x x x x with each x being eight bits in length, also known as an octet.
The total size of the address is 32 bits.
Please refer to the binary video.
If you're not sure about bits and how to convert this address into binary and back again.
IP addresses once again have a hierarchical structure to enable routing, which consists of two main
parts.
We have the network portion of an address and the host portion, and we'll look at that in more detail
in a moment.
IP addresses are used for routing in a very similar way to the way DHL or FedEx route parcels based
on a destination address.
Routers will route traffic to a destination address when unicast packets are transmitted.
Multicast packets use a different mechanism and do their routing based on source address.
So as an analogy, DHL or FedEx are sending the parcel to a destination based on the destination on
the parcel.
Routers are sending packets to destinations based on the destination address in the packet.