2.1 Compare & contrast Transmission Control Protocol (TCP) & User Datagram Protocol (UDP) ports, protocols, & their purpose Flashcards
What protocols in the TCP/IP suite handle port assignment?
TCP & UDP
Meaning of UDP?
User Datagram Protocol
How many port numbers do hosts assign?
2
Explain the port assignment process
Each host assigns a destination & source port
In the port assignment process, what does the destination port map to?
The requested service
i.e. HTTP on port 80
What is the source port in the port assignment process?
Random port number chosen by the client
i.e. 47747
The server replies using the client’s source port as its destination port & its own app port as the source port
How does TCP differ from UDP?
Providing reliable data delivery
What is TCP known as?
Connection-oriented protocol
How does TCP establish a connection between sender & recipient?
via Handshake sequence
List TCP’s handshake sequence packets
- SYN packet
- SYN/ACK packet
- ACK packet
What does TCP assign to each packet?
A sequence number
Why does TCP assign sequence numbers to packets?
So they can be tracked
In TCP, why do clients send ACK packets?
To acknowledge that a packet has been received
In TCP, why do clients send NACK packets?
For retransmission of a missing or damaged packet
NACK basically means Negative Acknowledgement
Main drawback of TCP?
Connection info increases packet size due to multiple header fields
When is TCP used?
When application protocols can’t tolerate missing or damaged info.
2 application protocols that must use TCP?
- HTTPS
- SSH
What is UDP known as?
Connectionless protocol
How does UDP differ from TCP?
Faster & not guaranteeing packet delivery or packet sequence order
When is UDP used?
When application protocols can tolerate missing/out-of-order packets
It’s often used for time-sensitive data like voice or video, where missing data causes glitches, not errors or connection failures.
Why is UDP faster than TCP?
UDP has reduced overhead
Overhead is the extra data or processing needed for communication, beyond the essential payload.
What can be used to control delivery reliability when using UDP?
Application layer
2 protocols that use UDP?
- DHCP
- TFTP
Why must DHCP use UDP?
DHCP uses broacast transmissions, which TCP doesn’t support
Broadcast sends data to all network devices at once.
If a response packet isn’t received, the client just restarts the provess & tries again repeatedly, until timing out
Meaning of TFTP?
Trivial File Transfer Protocol
Purpose of TFTP?
For network devices to obtain a configuration file
Why doesnt TFTP require TCP?
It has it’s own built-in mechanism for acknowledging messages
Meaning of FTP?
File Transfer Protocol
FTP–Data connection port?
This port handles actual file transfers
TCP/20
FTP–Control connection port?
This port manages commands & responses
TCP/21
Identify port
TCP/20
FTP-Data connection
Identify port
TCP/21
FTP-Control connection
Purpose of FTP?
Transfer files across a network
Meaning of SSH?
Secure Shell
Purpose of SSH protocol?
Make a secure connection to the command-line interface of a server
SSH protocol port?
TCP/22
Identify port
TCP/22
SSH
Purpose of Telnet protocol?
Make an unsecure connection to the command-line interface of a server