Chapter 3a - Networking Flashcards
What does TCP stand for and what exactly is it?
TCP stands for Transmission Control Protocol, and it’s a fundamental networking protocol that operates at the transport layer, and provides connection-oriented traffic and guaranteed delivery.
TCP uses on a “three way handshake” between a client and a server, i.e. two different source and destination IP addresses.
What is a three way handshake?
A three way handshake is the process of a client and server setting up a connection before exchanging data.
To start a TCP session:
- The client sends a SYN packet (standing for synchronize) to the server.
- The server responds with a SYN-ACK packet (synchronize/acknowledge)
- The client completes the third part of the handshake with an ACK packet to establish the connection
What does UDP stand for and what is it?
UDP stands for a User Datagram Protocol and is another fundamental transport layer protocol. The main difference between UDP and TCP is that UDP is a provides connectionless sessions without a three-way handshake.
What are common use cases for the two transport layer protocols, TCP and UDP?
TCP is primarily used when we care about our data getting from A to B reliably and safely in an ordered manner. TCP makes friends with the source first and sets up a connection before exchanging data.
Common use cases for TCP are file transfers, emailing, web browsing, remote desktop and database access.
UDP is primarily used when we care about speed and transferring our data very quickly. UDP doesn’t check to see if you received its message or wait for any verification, it just continuously sends data and hopes you get it all.
A good use case for UDP is for video streaming and online gaming.
What is ICMP?
ICMP stands for Internet Control Messaging Protocol and is used for testing basic connectivity between two systems.
It is commonly used in tools such as ping, pathping and tracert
What is IP
IP stands for internet protocol. It’s a protocol that assigns specific address to host within a network. There is typically one public IP address assigned to a router or network gateway, then a series of local IP addresses assigned by the router to the hosts on its local network via subnetting.
What is ARP?
ARP stands for Address Resolution Protocol and it’s a way for devices on a local network to resolve an IP address to a MAC address in order to communicate at the data link layer.
How does ARP work? Give me a hypothetical scenario.
If Device A knows the IP address, say 10.1.1.1 of Device B but not its MAC address, it needs the MAC to send data via the data link layer.
Device A sends out an ARP request broadcast message to all the devices on the local network asking “Who has IP address 10.1.1.1? Please tell me your MAC address.”
If Device B is on the same local network and has that IP address, it will respond directly to Device A with an ARP reply message containing its MAC address.
Device A receives the ARP reply and updates its ARP table, associating the IP address of Device B with its MAC address, and they can now send data directly to one another on the network.
Both devices will cache (store) this mapping for future use to avoid unnecessary ARP requests in the future.
How does a switch play into this forwarding process?
Switches operate at the data link layer and forward data frames between devices on a local network.
They map MAC addresses to the port to which each MAC address is reachable via CAM table or MAC address forwarding table.
*CAM stands for Content Addressable Memory.
