Computer Networks

Question 1

Explain the OSI model layers.

Answer 1

1. Physical: Electrical signals and hardware
2. Data Link: Frame formatting and error detection
3. Network: Routing and IP addressing
4. Transport: End-to-end communication (TCP/UDP)
5. Session: Managing connections between applications
6. Presentation: Data encryption, compression, formatting
7. Application: User interfaces and network services
   Each layer provides services to the layer above and uses services from the layer below.

Question 2

What is the difference between TCP and UDP?

Answer 2

TCP: Connection-oriented, reliable, ensures order, error checking, higher overhead. Used for web, email, file transfer.
UDP: Connectionless, fast, no delivery/order guarantee, lower overhead. Used for streaming, gaming, DNS.

Question 3

Explain how DNS works.

Answer 3

1. User requests website
2. Browser checks cache
3. Queries DNS resolver
4. Resolver queries root nameservers
5. Then TLD servers
6. Then authoritative nameservers
7. Returns IP
8. Browser connects using IP.

Question 4

What are different types of network topologies?

Answer 4

Bus, Star, Ring, Mesh, Tree, Hybrid. Each has pros and cons in cost, reliability, scalability, and performance.

Question 5

Explain network security protocols and measures.

Answer 5

Firewalls, VPN, SSL/TLS, IPSec, WPA/WPA2, NAC, IDS/IPS. Defense in depth using multiple layers.

Question 6

What is Quality of Service (QoS) in networks?

Answer 6

Manages resources for traffic. Techniques: Traffic Shaping, Prioritization, Classification, Policing, Queuing.

Question 7

Describe routing protocols and algorithms.

Answer 7

Distance Vector (RIP - Bellman-Ford), Link State (OSPF - Dijkstra), Path Vector (BGP), Static, Dynamic.

Question 8

What are VLANs and their benefits?

Answer 8

Virtual LANs segment networks logically. Types: Port/MAC/Protocol-based. Benefits: Security, isolation, flexibility.

Question 9

Explain network load balancing techniques.

Answer 9

Techniques: Round Robin, Least Connections, IP Hash, Geographic, Health Checks. Layer 4/7 balancing.

Question 10

What is Software-Defined Networking (SDN)?

Answer 10

Separates control and data plane. Components: Controller, OpenFlow, Apps, APIs. Benefits: Centralized control.

Question 11

Describe wireless networking standards and technologies.

Answer 11

802.11a/b/g/n/ac/ax (WiFi standards), Bluetooth, Cellular (3G/4G/5G). Vary by range, speed, power.

Question 12

What are network monitoring and troubleshooting tools?

Answer 12

Tools: Ping, Traceroute, Netstat, Wireshark, Nmap, SNMP, Bandwidth monitors. Troubleshoot via OSI layers.

Question 13

Explain Content Delivery Networks (CDNs).

Answer 13

CDNs use edge servers, caching, load balancing, and global distribution to reduce latency and improve performance.