This MCQ section contains Multiple choice questions on TCP/IP Protocol suite and protocols within it.
1. What does TCP/IP stand for?
a) Transmission Control Protocol / Internet Protocol
b) Transfer Control Protocol / Interconnected Protocol
c) Transmission Communication Protocol / Internet Pathway
d) Transport Connection Protocol / Internet Packet
Answer: a) Transmission Control Protocol / Internet Protocol
Explanation: TCP/IP is the foundational communication protocol suite for the Internet.
2. Which layer of the TCP/IP model corresponds to the OSI model’s Transport layer?
a) Network Access
b) Internet
c) Transport
d) Application
Answer: c) Transport
Explanation: The TCP/IP Transport layer (TCP/UDP) aligns with the OSI Transport layer.
3. What is the primary function of the Internet layer in TCP/IP?
a) Error detection and correction
b) Logical addressing and routing
c) Data encryption
d) Session management
Answer: b) Logical addressing and routing
Explanation: The Internet layer (IP) handles routing using IP addresses.
4. Which protocol operates at the Transport layer?
a) IP
b) HTTP
c) TCP
d) ARP
Answer: c) TCP
Explanation: TCP (Transmission Control Protocol) ensures reliable data delivery.
5. What is the purpose of the Network Access layer?
a) Packet routing
b) Physical transmission of data
c) Application data formatting
d) Encryption
Answer: b) Physical transmission of data
Explanation: This layer deals with hardware (Ethernet, Wi-Fi) and MAC addressing.
6. Which of the following is a connectionless protocol?
a) TCP
b) UDP
c) FTP
d) HTTP
Answer: b) UDP
Explanation: UDP (User Datagram Protocol) does not establish a connection before sending data.
7. What is the role of the Application layer in TCP/IP?
a) Encrypting data
b) Providing network services to applications
c) Assigning IP addresses
d) Error correction
Answer: b) Providing network services to applications
Explanation: Protocols like HTTP, FTP, and SMTP operate here.
8. Which layer is responsible for end-to-end communication?
a) Network Access
b) Internet
c) Transport
d) Application
Answer: c) Transport
Explanation: The Transport layer ensures data reaches the correct application (via ports).
9. What is the default port for HTTP?
a) 21
b) 25
c) 80
d) 443
Answer: c) 80
Explanation: HTTP uses port 80, while HTTPS uses 443.
10. Which protocol resolves IP addresses to MAC addresses?
a) DNS
b) DHCP
c) ARP
d) ICMP
Answer: c) ARP (Address Resolution Protocol)
Explanation: ARP maps IP addresses to MAC addresses in a local network.
11. Which protocol provides reliable, ordered data delivery?
a) UDP
b) TCP
c) ICMP
d) IGMP
Answer: b) TCP
Explanation: TCP ensures reliable and ordered data transmission.
12. What is a key advantage of UDP over TCP?
a) Error correction
b) Lower latency
c) Flow control
d) Retransmission of lost packets
Answer: b) Lower latency
Explanation: UDP is faster because it lacks connection setup and error recovery.
13. Which field in a TCP header ensures data integrity?
a) Sequence number
b) Checksum
c) Window size
d) Acknowledgment number
Answer: b) Checksum
Explanation: The checksum detects errors in the TCP segment.
14. What is the three-way handshake in TCP?
a) SYN, SYN-ACK, ACK
b) SYN, ACK, FIN
c) REQ, RES, ACK
d) SYN, SYN, SYN
Answer: a) SYN, SYN-ACK, ACK
Explanation: This establishes a TCP connection before data transfer.
15. What is VPN used for?
a) Secure remote access over public networks
b) Speed up Internet connections
c) Block ads
d) Assign static IPs
Answer: a) Secure remote access over public networks
Explanation: VPNs encrypt traffic for privacy and security.
16. Which protocol is used for real-time applications like VoIP?
a) TCP
b) UDP
c) FTP
d) SMTP
Answer: b) UDP
Explanation: VoIP (e.g., Zoom, Skype) prefers UDP for low latency.
17. What is the purpose of an IP address?
a) Identify a network interface
b) Provide error correction
c) Encrypt data packets
d) Manage MAC addresses
Answer: a) Identify a network interface
Explanation: IP addresses uniquely identify devices on a network for communication.
18. Which IPv4 address class is reserved for multicast?
a) Class A
b) Class B
c) Class C
d) Class D
Answer: d) Class D
Explanation: Class D (224.0.0.0 to 239.255.255.255) is used for multicast groups.
19. What is the loopback IPv4 address?
a) 192.168.0.1
b) 127.0.0.1
c) 10.0.0.1
d) 172.16.0.1
Answer: b) 127.0.0.1
Explanation: 127.0.0.1 is used for local loopback testing.
20. Which subnet mask corresponds to a /24 network?
a) 255.0.0.0
b) 255.255.0.0
c) 255.255.255.0
d) 255.255.255.255
Answer: c) 255.255.255.0
Explanation: A /24 subnet mask allows 256 addresses (254 usable).
21. What is the default subnet mask for a Class B network?
a) 255.0.0.0
b) 255.255.0.0
c) 255.255.255.0
d) 255.255.255.255
Answer: b) 255.255.0.0
Explanation: Class B (128.0.0.0 to 191.255.255.255) uses 255.255.0.0.
22. Which protocol dynamically assigns IP addresses?
a) DNS
b) DHCP
c) ARP
d) ICMP
Answer: b) DHCP (Dynamic Host Configuration Protocol)
Explanation: DHCP automates IP assignment (e.g., 192.168.1.x).
23. What is the maximum number of hosts in a /30 subnet?
a) 2
b) 4
c) 6
d) 8
Answer: a) 2
Explanation: A /30 subnet has 4 total addresses, but only 2 usable hosts (network & broadcast addresses occupy 2).
24. Which IPv6 address type is equivalent to IPv4’s 127.0.0.1?
a) ::1
b) FE80::
c) 2001::
d) FF00::
Answer: a) ::1
Explanation: ::1 is the IPv6 loopback address.
25. What does CIDR stand for?
a) Classless Inter-Domain Routing
b) Classful Internet Domain Routing
c) Controlled IP Data Routing
d) Centralized Internet Directory Registry
Answer: a) Classless Inter-Domain Routing
Explanation: CIDR replaced classful addressing for efficient IP allocation.
26. Which command checks IP configuration on Windows?
a) ifconfig
b) ipconfig
c) netstat
d) tracert
Answer: b) ipconfig
Explanation: ipconfig displays IP, subnet mask, and gateway (Linux uses ifconfig).
27. Which protocol is used for routing between autonomous systems?
a) RIP
b) OSPF
c) BGP
d) EIGRP
Answer: c) BGP (Border Gateway Protocol)
Explanation: BGP is the Internet’s backbone routing protocol.
28. What is the purpose of a default gateway?
a) Assign IP addresses
b) Route traffic to other networks
c) Resolve domain names
d) Filter malware
Answer: b) Route traffic to other networks
Explanation: The default gateway (usually a router) forwards packets outside the local network.
29. Which routing protocol uses hop count as a metric?
a) OSPF
b) BGP
c) RIP
d) EIGRP
Answer: c) RIP (Routing Information Protocol)
Explanation: RIP limits routes to 15 hops.
30. What does NAT do?
a) Encrypts data
b) Maps private IPs to a public IP
c) Blocks malware
d) Assigns MAC addresses
Answer: b) Maps private IPs to a public IP
Explanation: NAT (Network Address Translation) allows multiple devices to share one public IP.
31. Which protocol tests network connectivity?
a) DNS
b) ICMP
c) ARP
d) DHCP
Answer: b) ICMP (Internet Control Message Protocol)
Explanation: ICMP is used by ping and traceroute.
32. What is the TTL field in an IP packet?
a) Time-to-Live (prevents infinite loops)
b) Total Transmission Length
c) Type of Transport Layer
d) TCP Traffic Limiter
Answer: a) Time-to-Live (prevents infinite loops)
Explanation: TTL decrements at each router; if 0, the packet is discarded.
33. Which protocol updates routing tables dynamically?
a) ARP
b) OSPF
c) DNS
d) HTTP
Answer: b) OSPF (Open Shortest Path First)
Explanation: OSPF is a link-state routing protocol.
34. What is the purpose of a routing table?
a) Store MAC addresses
b) Determine the best path for packets
c) Encrypt data
d) Block unauthorized access
Answer: b) Determine the best path for packets
Explanation: Routers use tables to forward packets efficiently.
35. Which command traces the route to a destination?
a) ping
b) tracert (Windows) / traceroute (Linux)
c) netstat
d) nslookup
Answer: b) tracert / traceroute
Explanation: These show each hop between source and destination.
36. What is a VLAN?
a) Virtual Local Area Network (logical segmentation)
b) Virus-Locked Access Node
c) Visual LAN Analyzer
d) Variable Latency Adjustment Network
Answer: a) Virtual Local Area Network
Explanation: VLANs split a physical network into logical segments.
37. Which port does HTTPS use?
a) 80
b) 443
c) 22
d) 53
Answer: b) 443
Explanation: HTTPS encrypts traffic on port 443 (HTTP uses 80).
38. What is the purpose of a firewall?
a) Block unauthorized access
b) Assign IP addresses
c) Resolve DNS queries
d) Speed up data transfer
Answer: a) Block unauthorized access
Explanation: Firewalls filter traffic based on security rules.
39. Which protocol encrypts web traffic?
a) HTTP
b) FTP
c) SSL/TLS
d) SNMP
Answer: c) SSL/TLS
Explanation: SSL/TLS enables HTTPS (secure HTTP).
40. What is a common use of SSH?
a) Secure remote server access
b) Send emails
c) Host websites
d) Manage DNS records
Answer: a) Secure remote server access
Explanation: SSH (port 22) encrypts remote logins.
41. Which protocol is used for email transmission?
a) HTTP
b) SMTP
c) SNMP
d) ICMP
Answer: b) SMTP (Simple Mail Transfer Protocol)
Explanation: SMTP (port 25) sends emails between servers.
42. What does DNS do?
a) Assigns IP addresses
b) Maps domain names to IPs
c) Encrypts data
d) Blocks malware
Answer: b) Maps domain names to IPs
Explanation: DNS (e.g., google.com → 172.217.0.0).
43. Which protocol is used for file transfers?
a) HTTP
b) FTP
c) SNMP
d) DHCP
Answer: b) FTP (File Transfer Protocol)
Explanation: FTP (port 21) uploads/downloads files.
44. What is a DoS attack?
a) Denial-of-Service (overwhelming a server)
b) Data Encryption Standard
c) Domain Name System
d) Dynamic Operating System
Answer: a) Denial-of-Service
Explanation: DoS floods a target with traffic to crash it.
45. Which tool captures network packets?
a) Ping
b) Wireshark
c) Traceroute
d) Netstat
Answer: b) Wireshark
Explanation: Wireshark is a packet analyzer.