TCP and UDP

Who is responsible for DNS root zones, IP addressing, and protocol numbers?

Internet Assigned Numbers Authority (IANA)

What does IANA stand for?

Internet Assigned Numbers Authority

What does IANA coordinate globally?

IP addressing (IPv4 and IPv6) and Autonomous System Numbers

What organization does IANA coordinate with for protocol codes?

Internet Engineering Task Force (IETF)

What layers are defined by IEEE?

Physical and Data Link layers

What layer is IP in?

Network layer

What protocols operate at the transport layer?

TCP and UDP

What layer has many protocol options?

Application layer

What is UDP?

User Datagram Protocol, a connectionless and unreliable transport protocol

What is TCP?

Transmission Control Protocol, a connection-oriented and reliable transport protocol

What type of communication does UDP use?

Connectionless

What type of communication does TCP use?

Connection-oriented

What ensures reliability in TCP?

ACK (acknowledgment) protocol and sequencing

What is used to establish a TCP connection?

Three-way handshake

How is a TCP connection terminated?

Multi-step handshake (teardown)

What is the client/server model?

A client requests services and a server provides them

Can clients run multiple tasks at once?

Yes, clients can run multiple tasks concurrently

What is a multi-task server?

A server that provides multiple services using separate processes

What do routers use to forward packets?

Subnet (IP) address

What address is used to deliver frames to devices?

MAC address

What does the IP layer do?

Selects packets based on full IP address

What does the transport layer do?

Forwards data to tasks using port numbers

What is a port number?

An identifier for a specific task or service on a device

What does a server do with a port?

Listens on a designated port for incoming data

What type of ports do clients use?

Dynamic (ephemeral) ports

What is the size of a port number field?

16 bits

How many possible port numbers exist?

65,536

What are well-known ports?

Ports 0–1023 assigned by IANA

What are registered ports?

Ports 1024–49151 assigned by IANA

What are dynamic ports?

Ports 49152–65535 used by clients

What addressing levels are used in UDP?

Device-level (IP and MAC) and task-level (port number)

What does the UDP checksum do?

Detects data corruption

What are the fields in a UDP datagram?

Source port, destination port, length, checksum, data

What is the payload in UDP?

Data

What protocol does DHCP use?

UDP

What port does a DHCP client use?

Port 68

What port does a DHCP server use?

Port 67

What does a DHCP server provide?

IP address and network configuration

What are some applications that use UDP?

NTP, TFTP, SNMP, RTSP, RIP

What port does NTP use?

123

What port does TFTP use?

69

What ports does SNMP use?

161 and 162

What port does RTSP use?

554

What port does RIP use?

520

Why is UDP used?

For speed, low overhead, and time-sensitive applications

How are TCP ports used?

Same as UDP for identifying sender and receiver tasks

What must each client application use?

A unique dynamic port

What happens if multiple apps run on one device?

Each uses a different port number

What is a socket address?

A combination of IP address and port number

How is a TCP connection identified?

By two socket addresses (one for each endpoint)

What does the TCP sequence number represent?

The first byte of data in a segment

What is the purpose of sequence numbers?

Ordering and tracking data for reliability

What is the ACK number?

The next expected byte number

What are TCP control flags?

Bits that control connection behavior (SYN, ACK, FIN, etc.)

What does SYN do?

Synchronizes sequence numbers to start a connection

What does ACK do?

Indicates acknowledgment is valid

What does FIN do?

Terminates a connection

What does RST do?

Resets a connection

What is window size in TCP?

The amount of data the receiver can accept

What is the purpose of flow control?

Prevents overwhelming the receiver

What is MSS?

Maximum Segment Size

What does the TCP checksum do?

Error detection

What is the TCP three-way handshake?

A process to establish a connection between client and server

What happens in step 1 of the handshake?

Client sends SYN with sequence number

What happens in step 2 of the handshake?

Server responds with SYN + ACK

What happens in step 3 of the handshake?

Client sends ACK

How does TCP maintain a connection?

Using sequence numbers and acknowledgments

What are piggybacked ACKs?

ACKs included with data segments

What are standalone ACKs?

ACKs sent without data

How is a TCP connection terminated?

Using FIN and ACK segments in multiple steps

What does FIN indicate?

End of data transmission