Layer 4 port assignment

Answer 1

A rational number is any number that can be made by dividing oneinteger by another.0.5 is a rational number as it can be made by dividing the number 1by the number 22 is a rational number because it can be made by dividing 2 by 1-6.6 is a rational number because it can be made by dividing -66 by10---------------------------------------------------------Note there are number that are called Irrational Numbers.Irrational numbers are all "real" numbers (numbers with a decimalpoint) that cannot be written as a simple fraction - the decimalgoes on forever without repeating.For instance the number Pi is an irrational number.A rational number is a real number that can be expressed as a ratio of two integers. Another way to think about it is this: if you can write a number as a fraction then it's a rational number.

Answer 2

When data is sent across a network it is encapsulated at different layers of the OSI model. Mainly layer 2, 3, and 4. Layers 2 and 3 are intra and inter network data respectively. At layer 2 data is a frame and has a header that tells which type of media the frame will be transmitted over and a trailer that tells the receiving device if data has been corrupted. At layer 3 you have your IP addresses and network routing information, data here is called a packet. There is only a header at layer 3. Layer 4 is transport which encapsulates data as a Segment. This is where port assignments are important. Layer 4 ports are not to be confused with Layer 1 interfaces which are often also called ports, they are virtual ports that are used by the NIC to determine which protocol will handle the incoming data. From port 1 - 1023 are your well known ports usually used by servers, from 1024 to 49151 are registered ports and are opened by your machine as needed for the applicable services. They aren't as static as the Layer 3 ports but it makes it more difficult to know exactly which parts of your computer are open by assigning them custom assignments. The last set of ports, 49151 and up are your dynamic ports, which I don't know all that much about. The important thing to know about Layer 4 is the difference between TCP and UDP. Whether or not there is a connection between the two end devices and what kind of recovery the machines will perform in transmitting data determines whether or not the port is a UDP or TCP port. Data in forms of web pages and e-mails need to be delivered in full and without error in order for users to have the full experience and so that important information isn't lost in translation. These types of transmissions are handled with TCP or Transmission Control Protocol. In this case a connection is established and each frame is counted and reassembled in the correct order. In cases where data is corrupted at layer 2 and dropped the receiving device will tell the other device that it is missing important information and the sending device will retransmit. Because of the time that this takes segments in the form of videos and phone calls which experience a constant stream of data and are continuously open to segment loss TCP is not desirable. This is where UDP comes into play. Unreliable Delivery Protocol ports simply take data in as it goes and send it to the appropriate programming in what is called "Best effort" transmission. This means that missing sequence numbers are not retransmitted and there is no logical connection between the server sending the information and host receiving. The reason why assigning ports is important is because each port coordinates with its own protocol, or set of rules for handling the segments. You don't want e-mails which are handled and reassembled by TCP being pushed through a UDP port to a protocol that simply handles video streaming, nothing would happen. So assigning port numbers is important for a number of reasons, the most important being telling your computer how to handle the data that it is receiving. On your personal machine and company servers you may assign port numbers that are not well known to other devices, you may not want HTTP to run on just port 80, and you may not want mail going through the common 110 or 25 because you don't want intruders to know which ports they will have direct access to by default. Ultimately your computer will know which ports to assign, and in client mode (asking for data) it will automatically open a random port for the server to send data to. The server will usually have well known ports running because it's easier for client devices to figure out where to go to ask for the data that you need.

Answer 3

to identify the processes or services that are communicating within the end devices

Answer 4

deine mutter