Question

Computer Network Module 4  Transport Layer and Application Layer Short Explaination

Answer 1

Transport Layer: Imagine it as a reliable post office service for your data, making sure it arrives safely at its destination. The transport layer manages the delivery process.

Service Primitives: These are the commands you use to interact with the transport layer. When an application wants to send data, it says, "Hey, transport layer, please send this data." And when it receives data, it tells the transport layer, "I got this data."

Sockets: Sockets are like unique addresses for your computer, and they come in pairs: one for the sender and one for the receiver. It's like having a phone number and knowing who you're calling. It helps computers know where to send data and who's supposed to get it.

Connection Management (Handshake): Think of it as a three-step greeting between two computers. First, Computer 1 says, "Hi, can we talk?" Then Computer 2 replies, "Hi, yes, let's talk." Finally, Computer 1 says, "Great, let's start talking!" This ensures both computers are on the same page before they start sending data.

UDP (User Datagram Protocol): UDP is like sending quick notes or postcards. It's fast and doesn't guarantee delivery. If it doesn't arrive, you may not know. It's great for things like live video or online gaming, where speed matters more than making sure every piece of data gets there.

TCP (Transmission Control Protocol): TCP is like sending a certified letter. It guarantees the data will arrive and in the right order. However, it's a bit slower because it checks if the letter was received and asks for a signature to confirm delivery.

TCP State Transition: This is like a conversation with multiple phases. First, you say "Hi," then you exchange messages, and finally, you say "Goodbye." TCP has its own sequence of states to ensure a smooth conversation between computers.

TCP Timers: These are like alarm clocks. If one computer is waiting for a response, and it doesn't get it within a reasonable time, it'll set off an alarm to make sure the communication process keeps moving.

TCP Flow Control (Sliding Window): Think of it like managing the speed of data transfer. If the sender is sending data too quickly and the receiver can't keep up, it says, "Hey, slow down a bit." If it's ready for more, it says, "Send me more." This helps balance the flow of data.

 

Application Layer: Think of the Application Layer as the user-friendly part of the internet. It's where you interact with websites, send emails, and do various online activities. Here are some key protocols at this layer:

1. HTTP (Hypertext Transfer Protocol): HTTP is like the language that web browsers and web servers use to communicate. When you type a website address (URL) in your browser, HTTP helps request and display the web page.

2. SMTP (Simple Mail Transfer Protocol): SMTP is like the postal service for emails. It's responsible for sending, receiving, and relaying emails between email servers. When you hit "Send" on an email, SMTP handles the delivery.

3. Telnet: Telnet is like a remote control for a computer. It allows you to log into and control a remote computer as if you were sitting in front of it. Useful for system administrators.

4. FTP (File Transfer Protocol): FTP is like a courier service for files. It lets you upload and download files from a remote server. It's commonly used for managing websites and sharing files.

5. DHCP (Dynamic Host Configuration Protocol): DHCP is like a dynamic address assignment system. When you connect to a network (like your home Wi-Fi), DHCP assigns your device an IP address so that you can communicate on the network.

6. DNS (Domain Name System): DNS is like a phone book for the internet. It translates human-friendly domain names (like www.example.com) into IP addresses that computers use to find websites. It makes it easier to navigate the web.

Types of Name Servers: Within DNS, there are different types of name servers:

• Authoritative Name Servers: These are like the main libraries that have all the information about a specific domain. They know the IP addresses associated with a domain name.

• Recursive Name Servers: Think of these as helpful librarians. When you make a request for a website (e.g., www.example.com), they find the authoritative name server for that domain and retrieve the IP address for you.

• Root Name Servers: These are like the top-level librarians. They have a list of authoritative name servers for different top-level domains (like .com, .org, .net). When you're looking for a specific domain, they direct you to the right place.