Supernetting MCQs

1. What is the purpose of supernetting?

a) To merge multiple smaller networks into a larger network b) To divide a large network into smaller subnets c) To improve security in networking d) To increase the number of available hosts in a subnet

Correct Answer: a) To merge multiple smaller networks into a larger network

Explanation:
Supernetting (or route aggregation) combines multiple contiguous smaller networks into a larger network block. This reduces routing table entries and improves efficiency, opposite to subnetting which divides networks.

2. Supernetting is commonly used in which type of addressing?

a) IPv4 b) IPv6 c) CIDR (Classless Inter-Domain Routing) d) ARP

Correct Answer: c) CIDR (Classless Inter-Domain Routing)

Explanation:
Supernetting is a key feature of CIDR, which eliminated classful boundaries. While it can be used with both IPv4 and IPv6, it's specifically enabled by CIDR notation which allows flexible prefix lengths.

3. Which of the following is a valid example of supernetting?

a) Combining 192.168.1.0/24 and 192.168.2.0/24 into 192.168.0.0/23 b) Splitting 10.0.0.0/8 into 10.0.0.0/16 c) Assigning a subnet mask of 255.255.255.248 d) Using a /30 subnet mask

Correct Answer: a) Combining 192.168.1.0/24 and 192.168.2.0/24 into 192.168.0.0/23

Explanation:
This combines two /24 networks into one /23 supernet. The key requirements for supernetting are: contiguous networks, same size subnets, and power-of-2 number of networks to combine.

4. Which of the following is NOT true about supernetting?

a) Reduces the number of routing table entries b) Uses smaller subnet masks c) Increases the number of available networks d) Used in CIDR notation

Correct Answer: c) Increases the number of available networks

Explanation:
Supernetting actually decreases the number of networks by combining them. It reduces routing table entries (a), uses larger (not smaller) networks with smaller subnet masks (b), and is implemented through CIDR (d).

5. What is the supernet mask for combining 172.16.0.0/24 and 172.16.1.0/24?

a) 255.255.254.0 (/23) b) 255.255.255.0 (/24) c) 255.255.252.0 (/22) d) 255.255.248.0 (/21)

Correct Answer: a) 255.255.254.0 (/23)

Explanation:
To combine two /24 networks, we need a /23 supernet (one less bit in the mask). The subnet mask for /23 is 255.255.254.0, which covers both 172.16.0.0 and 172.16.1.0.

6. What is the main advantage of CIDR over classful addressing?

a) Reduces IP address wastage b) Increases the number of IP addresses available c) Eliminates the need for DHCP d) Improves TCP performance

Correct Answer: a) Reduces IP address wastage

Explanation:
CIDR's primary benefit is more efficient IP address allocation by allowing variable-length subnet masks. It doesn't create more addresses (b), still needs DHCP (c), and doesn't directly affect TCP (d).

7. How many contiguous /24 networks can be combined into a /21 supernet?

a) 4 b) 8 c) 16 d) 32

Correct Answer: b) 8

Explanation:
The difference in prefix lengths is 21-24 = 3 bits. Number of networks = 2³ = 8. A /21 supernet can contain 8 contiguous /24 networks.

8. Which of the following networks can be supernetted with 10.0.8.0/24?

a) 10.0.9.0/24 b) 10.0.16.0/24 c) 10.0.4.0/24 d) 10.0.7.0/24

Correct Answer: d) 10.0.7.0/24

Explanation:
For supernetting, networks must be contiguous. 10.0.7.0/24 is adjacent to 10.0.8.0/24 (7 and 8 are consecutive). The others are not contiguous (9 is next to 8, but would need to be combined with 8-15 for a /20 supernet).

9. What is the broadcast address of the supernet 172.16.0.0/20?

a) 172.16.15.255 b) 172.16.255.255 c) 172.16.0.255 d) 172.16.16.255

Correct Answer: a) 172.16.15.255

Explanation:
A /20 supernet includes 16 Class C networks (172.16.0.0 to 172.16.15.0). The broadcast address is the last address in this range: 172.16.15.255.

10. Which routing protocol benefits most from supernetting?

a) RIP b) OSPF c) BGP d) EIGRP

Correct Answer: c) BGP

Explanation:
BGP (Border Gateway Protocol) benefits most from supernetting as it handles Internet routing tables. Supernetting (route aggregation) significantly reduces the size of BGP tables, improving efficiency in global routing.

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