Is it true that UDP is always worse than TCP because it is unreliable.?

UDP is preferred for applications where prompt delivery is more critical than guaranteed delivery or ordering.

Is it true that All ports are equal.?

Ports below 1024 are reserved in Unix and require superuser access.

Network Programming: Sockets & Protocols

Network programming enables communication between processes on local or remote hosts using standard protocols like TCP and UDP via socket abstractions.

Core Principles

Client-Server Paradigm: Servers provide services and wait for requests; clients consume services and initiate connections.
Socket Abstraction: A communication endpoint used to speak to other programs using standard Unix file descriptors.
TCP (Transmission Control Protocol): Connection-oriented, reliable, full-duplex byte stream service.
UDP (User Datagram Protocol): Connectionless, unreliable datagram delivery service; prioritizes speed over accuracy.
Encapsulation: Data moves down the protocol stack, adding headers at each layer (e.g., TCP segment, IP datagram, Ethernet frame).
Port Numbers: 16-bit integers used to differentiate processes; ranges include Well-known (0-1023), Registered (1024-49151), and Dynamic/Private (49152-65535).

Key Terms

Socket API (SOCK_STREAM/SOCK_DGRAM)::
: Interface for network communication; Stream for TCP, Datagram for UDP.
Ephemeral Port::
: Short-lived port assigned automatically to a client.
Iterative Server::
: Server that handles one request at a time (typical for UDP).
Concurrent Server::
: Server that spawns a child process or thread for each connection (typical for TCP).
Demultiplexing::
: Process of stripping headers as data moves up the protocol stack at the destination.

Pro Tips

Use /etc/services on your Unix system to look up well-known port mappings.
TCP uses an 'advertised window' to prevent a fast sender from overwhelming a slow receiver's buffer.
A socket is identified by an IP address and a port number.

Pitfalls to Avoid

Missing lectures, labs, or tutorials, as exams are based on all delivery components.
Committing academic offenses like plagiarism, collusion, or falsification.
Assuming TCP preserves message boundaries (it is a byte stream service).
Neglecting to handle retransmissions or flow control in custom protocols.

Myth vs Reality

UDP is always worse than TCP because it is unreliable.: UDP is preferred for applications where prompt delivery is more critical than guaranteed delivery or ordering.
All ports are equal.: Ports below 1024 are reserved in Unix and require superuser access.