1. How many classes exist in classful IP addressing?
Correct Answer: c) 5
Explanation: Classful IP addressing has 5 classes: A, B, C (for unicast), D (for multicast), and E (reserved for experimental use). Classes A-C are used for regular host addressing with different network/host portions.
2. Which of the following is a valid Class A IP address?
Correct Answer: b) 10.0.0.1
Explanation: Class A addresses range from 1.0.0.1 to 126.255.255.254 (first octet 1-126). 192.168.1.1 is Class C, 172.16.0.1 is Class B, and 224.0.0.1 is Class D (multicast).
3. What is the default subnet mask for a Class B IP address?
Correct Answer: b) 255.255.0.0
Explanation: Classful addressing uses fixed subnet masks: Class A (255.0.0.0), Class B (255.255.0.0), and Class C (255.255.255.0). These masks divide the network and host portions of the address.
4. The first octet of a Class C address ranges from:
Correct Answer: c) 192 - 223
Explanation: Class C addresses have first octet range 192-223. Class A (1-126), Class B (128-191), Class D (224-239 for multicast), and Class E (240-255 for experimental).
5. Which class of IP addresses is used for multicast?
Correct Answer: d) Class D
Explanation: Class D addresses (224.0.0.0 to 239.255.255.255) are reserved for multicast groups where packets are delivered to multiple hosts simultaneously, unlike unicast (Classes A-C) or broadcast.
6. What is the maximum number of host addresses in a Class C network?
Correct Answer: a) 254
Explanation: Class C has 8 host bits (last octet), allowing 2^8 = 256 total addresses. Subtract 2 for network (x.x.x.0) and broadcast (x.x.x.255) addresses, leaving 254 usable host addresses.
7. What is CIDR in IP addressing?
Correct Answer: a) Classless Inter-Domain Routing
Explanation: CIDR (Classless Inter-Domain Routing) was introduced in 1993 to replace classful addressing. It allows for variable-length subnet masking (VLSM) and more efficient allocation of IP addresses.
8. In CIDR notation, what does /29 represent?
Correct Answer: c) 29-bit subnet mask
Explanation: The number after the slash (/) in CIDR notation indicates the number of bits in the subnet mask. /29 means the first 29 bits are network bits, leaving 3 bits for hosts (32-29=3).
9. What is the purpose of CIDR?
Correct Answer: d) All of the above
Explanation: CIDR was designed to: (1) Reduce routing table size through route aggregation, (2) Allow flexible subnet sizes with VLSM, and (3) Improve address space utilization by eliminating class boundaries.
10. What is the subnet mask for 192.168.1.0/27?
Correct Answer: b) 255.255.255.224
Explanation: /27 means 27 network bits, leaving 5 host bits. The subnet mask in binary is 27 ones followed by 5 zeros: 11111111.11111111.11111111.11100000, which converts to 255.255.255.224.
11. How many usable IP addresses are available in a /30 subnet?
Correct Answer: b) 2
Explanation: A /30 subnet has 2 host bits (32-30), allowing 4 total addresses (2^2). Subtract 2 for network and broadcast addresses, leaving 2 usable host addresses. Commonly used for point-to-point links.
12. If an ISP provides an IP range of 200.1.1.0/28, how many valid host addresses are available?
Correct Answer: a) 14
Explanation: A /28 subnet has 4 host bits (32-28), allowing 16 total addresses (2^4). Subtract 2 for network and broadcast addresses, leaving 14 usable host addresses. This is a common subnet size for small networks.
13. What is the primary difference between classful and classless addressing?
Explanation: The key differences are: (1) Classless uses VLSM while classful has fixed masks, (2) Classless eliminates rigid class boundaries, (3) Classless enables route aggregation (supernetting), and (4) Classless provides more efficient address space utilization.