# Multiple Choice Questions - Computer Networks ## OSI Model MCQs Question 1: Which layer of the OSI model is responsible for routing packets between different networks? A) Data Link Layer B) Transport Layer C) Network Layer D) Session Layer Answer: C - Network Layer handles routing using IP addresses. Question 2: Which device operates at Layer 2 of the OSI model? A) Hub B) Router C) Switch D) Repeater Answer: C - Switch operates at Layer 2 using MAC addresses. Question 3: What is the PDU name at the Transport layer? A) Bit B) Frame C) Packet D) Segment Answer: D - Segment is the PDU at the Transport layer for TCP. Question 4: Which layer is responsible for encryption and compression? A) Application Layer B) Presentation Layer C) Session Layer D) Transport Layer Answer: B - Presentation Layer handles encryption, compression, and data translation. Question 5: The Data Link layer uses which type of address? A) IP Address B) Port Number C) MAC Address D) Domain Name Answer: C - Data Link layer uses MAC addresses. ## TCP/IP MCQs Question 6: Which protocol provides reliable connection-oriented delivery? A) UDP B) TCP C) IP D) ICMP Answer: B - TCP is connection-oriented and provides reliable delivery. Question 7: What is the default port for HTTPS? A) 80 B) 21 C) 443 D) 22 Answer: C - HTTPS uses port 443. Question 8: Which protocol automatically assigns IP addresses to devices? A) DNS B) FTP C) DHCP D) SNMP Answer: C - DHCP automatically assigns IP addresses. Question 9: What does DNS stand for? A) Data Network System B) Domain Name System C) Dynamic Network Service D) Data Name Server Answer: B - DNS stands for Domain Name System. Question 10: Which protocol is used to send email? A) POP3 B) IMAP C) SMTP D) FTP Answer: C - SMTP is used to send email. ## IP Addressing MCQs Question 11: How many bits are in an IPv4 address? A) 16 B) 32 C) 64 D) 128 Answer: B - IPv4 addresses are 32 bits long. Question 12: What is the subnet mask for a /24 network? A) 255.0.0.0 B) 255.255.0.0 C) 255.255.255.0 D) 255.255.255.128 Answer: C - /24 means 24 network bits giving 255.255.255.0. Question 13: Which address range is a private Class C address? A) 10.0.0.0 to 10.255.255.255 B) 172.16.0.0 to 172.31.255.255 C) 192.168.0.0 to 192.168.255.255 D) 169.254.0.0 to 169.254.255.255 Answer: C - 192.168.0.0/16 is the private Class C range. Question 14: How many usable hosts does a /26 subnet have? A) 30 B) 62 C) 126 D) 254 Answer: B - /26 has 6 host bits giving 2^6 - 2 = 62 usable hosts. Question 15: What is the loopback address? A) 0.0.0.0 B) 10.0.0.1 C) 127.0.0.1 D) 192.168.1.1 Answer: C - 127.0.0.1 is the loopback address. ## Routing MCQs Question 16: Which routing protocol uses hop count as its metric? A) OSPF B) EIGRP C) BGP D) RIP Answer: D - RIP uses hop count as its metric with maximum 15 hops. Question 17: What is the maximum hop count in RIP? A) 10 B) 15 C) 16 D) 255 Answer: B - RIP maximum hop count is 15. 16 means unreachable. Question 18: Which protocol is used between autonomous systems on the internet? A) OSPF B) EIGRP C) BGP D) RIP Answer: C - BGP is the exterior gateway protocol used between autonomous systems. Question 19: What algorithm does OSPF use to calculate shortest paths? A) Bellman-Ford B) Dijkstra C) DUAL D) Floyd-Warshall Answer: B - OSPF uses Dijkstra's Shortest Path First algorithm. Question 20: What is administrative distance used for? A) To measure network latency B) To select between routes from different routing sources C) To count hops to a destination D) To calculate bandwidth Answer: B - Administrative distance determines which route source is preferred when multiple sources provide a route to the same destination. ## Security MCQs Question 21: Which encryption uses the same key for encryption and decryption? A) Asymmetric encryption B) Public key encryption C) Symmetric encryption D) Hashing Answer: C - Symmetric encryption uses the same key for both operations. Question 22: What does SSL/TLS provide? A) IP address assignment B) Encrypted communication C) Routing decisions D) DNS resolution Answer: B - SSL/TLS provides encrypted communication for HTTPS and other protocols. Question 23: What type of attack sends huge volumes of traffic to overwhelm a target? A) Man in the middle B) SQL injection C) DDoS D) Phishing Answer: C - DDoS Distributed Denial of Service floods the target with traffic. Question 24: Which device monitors and controls network traffic based on security rules? A) Switch B) Hub C) Router D) Firewall Answer: D - Firewall monitors and controls traffic based on configured security rules. Question 25: What does VPN stand for? A) Virtual Protocol Network B) Virtual Private Network C) Verified Public Network D) Variable Packet Network Answer: B - VPN stands for Virtual Private Network.