20 Subnetting Practice Questions and Answers

Improve your IPv4 Subnetting skills with Subnetting Quiz 2! In this quiz, you will find 20 Subnetting Practice Questions covering subnet masks, network and broadcast addresses, usable host ranges, binary conversions and subnet planning. Solve these Subnetting Questions, test your knowledge and get better prepared for the CCNA exam.

Subnetting Questions – Quiz 2

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Question 1

Which of the following IPv4 addresses belongs to Class B in classful addressing?

A	10.20.30.40
B	224.0.0.10
C	200.100.50.25
D	172.20.15.5
E	192.168.10.1

Question 2

What is the last usable host address in the IPv4 network 103.54.99.0/25?

A	103.54.99.255
B	103.54.99.1
C	103.54.99.128
D	103.54.99.254
E	103.54.99.126

Question 2 Explanation:

A /25 subnet contains 128 addresses. The network address is 103.54.99.0, the broadcast address is 103.54.99.127, and the last usable host address is 103.54.99.126.

Question 3

A network engineer needs to divide 192.168.10.0/24 into at least 10 equal-sized subnets. Which subnet mask provides the maximum number of usable hosts per subnet while meeting this requirement?

A	255.255.255.254
B	255.255.255.240
C	255.255.255.248
D	255.255.255.128
E	255.255.255.192

Question 3 Explanation:

Borrowing 4 host bits from a /24 creates 16 equal-sized /28 subnets. Each subnet provides 14 usable host addresses.

Question 4

In a traditional IPv4 subnet with a /30 prefix, which two addresses are reserved and cannot be assigned to hosts?

A	Default gateway and DNS server
B	Network address and broadcast address
C	Router ID and subnet mask
D	Loopback address and multicast address
E	First usable host and last usable host

Question 4 Explanation:

In a traditional IPv4 /30 subnet, the first address identifies the network and the last address is the directed broadcast address. The two addresses between them can be assigned to hosts.

Question 5

What is the 8-bit binary equivalent of the decimal number 245?

A	11101101
B	10010101
C	11110111
D	11110101
E	11110110

Question 6

A network engineer needs a subnet that supports at least 10 usable IPv4 host addresses. Which subnet mask provides the smallest suitable subnet?

A	255.255.255.252
B	255.255.255.240
C	255.255.255.128
D	255.255.255.254
E	255.255.255.248

Question 6 Explanation:

A /28 subnet provides 16 total addresses and 14 usable host addresses. A /29 supports only 6 usable hosts, so /28 is the smallest suitable subnet.

Question 7

Which IPv4 address class does 192.168.100.5 belong to in classful addressing?

A	B
B	C
C	D
D	E
E	A

Question 7 Explanation:

Class C addresses have a first octet between 192 and 223. Therefore, 192.168.100.5 belongs to Class C.

Question 8

A network engineer is given the IPv4 address 10.77.82.9/25. Which of the following addresses belongs to the same subnet and can be assigned to a host?

A	10.77.82.128
B	10.77.82.127
C	10.77.81.126
D	10.77.82.100
E	10.77.82.0

Question 8 Explanation:

The address 10.77.82.9/25 belongs to the network 10.77.82.0/25. Its usable host range is 10.77.82.1–10.77.82.126, making 10.77.82.100 a valid host address.

Question 9

Which usable host range contains the IPv4 address 72.15.146.1/25?

A	72.15.146.1 – 72.15.146.254
B	72.15.146.0 – 72.15.146.255
C	72.15.146.1 – 72.15.146.126
D	72.15.146.128 – 72.15.146.254
E	72.15.146.0 – 72.15.146.127

Question 9 Explanation:

The address belongs to the network 72.15.146.0/25. Its network address is 72.15.146.0 and its broadcast address is 72.15.146.127, leaving the usable host range 72.15.146.1–72.15.146.126.

Question 10

Which of the following is the correct binary representation of the IPv4 address 10.170.81.10?

A	00001010.11101010.01110001.00111010
B	00001010.11101010.01110001.00001011
C	00001010.11101010.01110001.00001010
D	00001010.10101010.01010001.00001010
E	00001010.11101010.01110001.11001010

Question 11

Which IPv4 subnet contains the host address 100.105.81.5/29?

A	100.105.81.16/29
B	100.105.81.64/29
C	100.105.81.8/29
D	100.105.81.0/29
E	100.105.81.32/29

Question 11 Explanation:

A /29 subnet has a block size of 8 in the fourth octet. The address 100.105.81.5 belongs to the network 100.105.81.0/29, with a usable host range of 100.105.81.1–100.105.81.6.

Question 12

What is the decimal equivalent of the 8-bit binary number 11001110?

A	180
B	182
C	200
D	206
E	204

Question 13

What is the first usable host address in the IPv4 network 10.100.12.0/26?

A	10.100.12.1
B	10.100.12.254
C	10.100.12.0
D	10.100.10.1
E	10.100.10.255

Question 13 Explanation:

The network address is 10.100.12.0, and the broadcast address is 10.100.12.63. The first usable host address is 10.100.12.1

Question 14

What is the dotted-decimal subnet mask for an IPv4 /25 prefix?

A	255.255.255.192
B	255.255.255.252
C	255.255.255.248
D	255.255.255.240
E	255.255.255.128

Question 14 Explanation:

A /25 prefix uses 25 network bits, leaving 7 host bits. Its dotted-decimal subnet mask is 255.255.255.128.

Question 15

What is the correct binary representation of the subnet mask 255.255.254.0?

A	11111111.11111111.11111100.00000000
B	11111111.11111111.11111111.00000000
C	11111111.11111111.11111000.00000000
D	11111111.11111111.11111110.10000000
E	11111111.11111111.11111110.00000000

Question 16

A company has the network 192.168.75.0/24 and needs at least 3 equal-sized subnets. Each subnet must support at least 60 usable host addresses. Which subnet mask meets both requirements?

A	255.255.255.240
B	255.255.255.248
C	255.255.255.192
D	255.255.255.128
E	255.255.255.224

Question 16 Explanation:

A /26 mask divides a /24 network into 4 equal-sized subnets, each providing 62 usable host addresses. This satisfies both requirements.

Question 17

What is the network address of the IPv4 host 10.100.75.8/25?

A	10.100.75.254/25
B	10.100.75.10/25
C	10.100.75.1/25
D	10.100.75.0/25
E	10.100.75.255/25

Question 17 Explanation:

A /25 subnet has a block size of 128 in the fourth octet. The address 10.100.75.8 belongs to the network 10.100.75.0/25.

Question 18

How many usable IPv4 host addresses are available in a standard subnet with mask 255.255.255.192?

A	62
B	60
C	64
D	32
E	30

Question 18 Explanation:

A /26 subnet leaves 6 host bits, providing 64 total IPv4 addresses. Excluding the network and broadcast addresses leaves 62 usable host addresses.

Question 19

What is the broadcast address of the IPv4 subnet containing 10.102.7.0/19?

A	10.102.32.255
B	10.102.31.255
C	10.102.255.255
D	10.102.31.0
E	10.102.32.1

Question 19 Explanation:

A /19 subnet uses the mask 255.255.224.0, creating blocks of 32 in the third octet. The address belongs to 10.102.0.0/19, whose broadcast address is 10.102.31.255.

Question 20

A company divides the network 192.168.7.0/24 into equal-sized /28 subnets. How many subnets are created, and how many usable host addresses are available in each subnet?

A	8 subnets, 30 usable hosts
B	32 subnets, 14 usable hosts
C	16 subnets, 14 usable hosts
D	16 subnets, 30 usable hosts
E	32 subnets, 6 usable hosts

Question 20 Explanation:

Moving from /24 to /28 borrows 4 bits, creating 16 subnets. Each /28 subnet leaves 4 host bits, providing 2⁴ − 2 = 14 usable host addresses.

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gokhankosem

Gokhan Kosem is a Network Engineer, Instructor and the Founder of IPCisco.com with 15+ years of experience in Cisco, Nokia, Huawei, Juniper, Linux, Service Provider Networks, Routing and Switching technologies.

He has worked on the backbone networks of major service providers and network vendors including Nortel, Alcatel-Lucent (Nokia) and has extensive hands-on experience with Cisco, Huawei, Juniper and Nokia networking technologies.

He has trained thousands of networking students worldwide through IPCisco.com, Udemy, books, labs, quizzes, and educational content across multiple social media platforms.

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Subnetting Quiz 2

Subnetting Questions – Quiz 2

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