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Welcome back.

Before we proceed with scanning, I just want to give a basic overview of DCP and UDP protocol for anyone

that is encountering it for the first time.

We already mentioned what TCP and UDP are.

They are two different protocols used for sending bits of data or also known as packets.

DCP and UDP are not the only protocols that are out there.

However, they are the most widely used ones.

Let's talk about DCP first.

So DCP stands for Transmission Control Protocol and it is the most commonly used protocol on the Internet.

When you load a webpage, your computer is sending DCP packets to the Web server address, asking it

to send a Web page to you.

Then the Web server responds by sending a stream of DCP packets, which are Web browser stages together

to form the Web page that you see.

The same happens once you, for example, click on a link or Sinding or post a comment on your Web browser,

sends DKP packets to the Web server and the server sends DSP packets back.

However, this is not a one way communication.

The remote system sends packets back to acknowledge that it received your packets.

So this is based on three way handshake.

And as the name says, three way handshake is consistent out of three steps.

First one is sent in the step.

The client wants to establish a connection with the server.

So it sends a segment within.

And what sin stands for is synchronize sequence number, which informs server that client wants to start

communication and with what sequence number eight starts the segments with.

After the same step comes the Cenac, which is the second step, and in the step, the server responds

to the client's request with Sinak signal, which set back signifies the responsive segment it received

and seen, is the same from the first step.

It signifies with what sequence number it is going to start this segment with in the third and final

step, which is just ekh.

In this step, the client acknowledges the response of server and they both establish a reliable connection

with which they will start the actual data transfer.

This is just an example of DCP communication establishing between a client and a server.

Once the data transfer starts, DCP guarantees the receiver will get the packets in order by numbering

them.

Then the server sends messages back to the sender, saying it received the messages or packets.

If the sender does not get the correct response, it will resend the packets to ensure the server got

the packets.

All of those packets are also checked for errors.

So TCP is all about reliability packets and with DCP are tracked, so no data is lost or corrupted in

transit.

That's why once you download the file, for example, over the Internet, your file is working once

you run it in your machine because it is being transferred with DCB, so all the packets will reach

their destination without any errors.

Euterpe, on the other hand, stands for user data protocol and data is the same thing as a packet of

information.

And UDP protocol works similarly to Tsipi, but it throws all the error checking stuff out.

That's why UDP is much faster.

It is used when speed is desirable and error correction is not necessary.

For example, UTP is frequently used for live broadcasts and online games.

That's why UDP doesn't really care whether packets received its destination and it will not send the

packet.

If it didn't reach the other part, it will just continue sending other packets.

You cannot ask for those packets again with would.

And these are just the basics behind to most known protocols for communication.

Even though many of you probably knew this already, it is good to have a refresher since we're going

to need this knowledge once performing, scanning.

See you in the next video.