What is the OSI model, and why is it important?
A 7-layer framework (Physical, Data Link, Network, Transport, Session, Presentation, Application) used to understand and design network protocols and troubleshoot issues.
Which protocols commonly use TCP ports 80, 443, 21, 22, and 25?
80: HTTP
443: HTTPS
21: FTP
22: SSH
25: SMTP
What is TCP’s three-way handshake process?
SYN -> SYN/ACK -> ACK. This establishes a reliable connection between client and server.
How do TCP and UDP differ?
TCP is connection-oriented and reliable with a three-way handshake.
UDP is connectionless and faster, but less reliable.
Define subnetting.
Dividing a network into smaller logical segments to optimize traffic, improve security, and reduce broadcast domains.
What is ARP, and how can it be exploited?
Address Resolution Protocol maps IP addresses to MAC addresses. Attackers can use ARP spoofing/poisoning to redirect or sniff network traffic.
What are common network attack types?
DoS/DDoS, MITM (Man in the Middle), IP spoofing, session hijacking.