Subnetting Questions Flashcards by Serg Gray

Subnet Zero

In the past, this website also provided questions relating to old routing kit that did not allow the use of the all “1” subnet or all the “0” subnet (known as ‘subnet zero’). The majority of site users are revising for cisco exams so the questions have been removed to avoid confusion.
On this website, and on all new cisco routers, the number of subnets is calculated using the formula of 2^n by default. However, for legacy routers network engineers use 2^n - 2 to comply with the almost obselete RFC 1878 standard. Some text books and courses that relate to old routing equipment also refer to the old formula as do some Microoft Learning courses. If you’re planning to take a non-Cisco exam that involves subnetting you should make sure you understand the ‘subnet zero’ concept’ and check what is considered the default correct formula by your examining board. Cisco’s position on subnet zero is stated here.

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Question: What is the first valid host on the subnetwork that the node 172.24.159.244 255.255.254.0 belongs to?

Answer: 172.24.158.1

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Question: What is the first valid host on the subnetwork that the node 172.29.24.25/25 belongs to?

Answer: 172.29.24.1

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Question: What is the first valid host on the subnetwork that the node 172.21.155.145/23 belongs to?

Answer: 172.21.154.1

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Question: Which subnet does host 172.17.254.166 255.255.255.192 belong to?

Answer: 172.17.254.128

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Question: Which subnet does host 172.28.39.245 255.255.254.0 belong to?

Answer: 172.28.38.0

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Question: What is the broadcast address of the network 172.18.236.0 255.255.252.0?

Answer: 172.18.239.255

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Question: Which subnet does host 172.20.6.188 255.255.254.0 belong to?

Answer: 172.20.6.0

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Question: What is the last valid host on the subnetwork 192.168.155.168 255.255.255.248?

Answer: 192.168.155.174

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Question: What valid host range is the IP address 172.30.167.104/24 a part of?

Answer: 172.30.167.1 through to 172.30.167.254

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Question: What valid host range is the IP address 10.141.252.111 255.255.240.0 a part of?

Answer: 10.141.240.1 through to 10.141.255.254

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Question: What is the broadcast address of the network 192.168.103.60/30?

Answer: 192.168.103.63

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Question: What is the broadcast address of the network 172.22.160.0/21?

Answer: 172.22.167.255

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Question: Which subnet does host 10.19.53.68 255.255.240.0 belong to?

Answer: 10.19.48.0

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Question: Which subnet does host 192.168.112.14 255.255.255.248 belong to?

Answer: 192.168.112.8

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Question: What valid host range is the IP address 192.168.124.209 255.255.255.240 a part of?

Answer: 192.168.124.209 through to 192.168.124.222

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Question: What is the last valid host on the subnetwork 172.28.3.0/27?

Answer: 172.28.3.30

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Question: What valid host range is the IP address 10.120.130.20 255.255.240.0 a part of?

Answer: 10.120.128.1 through to 10.120.143.254

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Question: What is the broadcast address of the network 172.18.152.0/21?

Answer: 172.18.159.255

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Question: How many subnets and hosts per subnet can you get from the network 192.168.108.0 255.255.255.240?

Answer: 16 subnets and 14 hosts

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Question: Which subnet does host 172.29.38.150 255.255.252.0 belong to?

Answer: 172.29.36.0

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Question: What is the last valid host on the subnetwork 172.28.172.128 255.255.255.128?

Answer: 172.28.172.254

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Question: What is the last valid host on the subnetwork 10.206.224.0 255.255.240.0?

Answer: 10.206.239.254

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Question: Which subnet does host 192.168.149.160/26 belong to?

Answer: 192.168.149.128

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Question: Which subnet does host 192.168.3.212 255.255.255.240 belong to?

Answer: 192.168.3.208

Question: Which subnet does host 192.168.101.6/28 belong to?

Answer: 192.168.101.0

Question: What valid host range is the IP address 192.168.37.156 255.255.255.240 a part of?

Answer: 192.168.37.145 through to 192.168.37.158

Question: What is the first valid host on the subnetwork that the node 192.168.101.36 255.255.255.224 belongs to?

Answer: 192.168.101.33

Question: Which subnet does host 172.22.123.211/23 belong to?

Answer: 172.22.122.0

Question: Which subnet does host 172.19.231.63 255.255.240.0 belong to?

Answer: 172.19.224.0

Question: Which subnet does host 172.24.114.79/23 belong to?

Answer: 172.24.114.0

Question: What is the broadcast address of the network 10.27.16.0/20?

Answer: 10.27.31.255

Question: Which subnet does host 172.16.123.219 255.255.254.0 belong to?

Answer: 172.16.122.0

Question: How many subnets and hosts per subnet can you get from the network 172.19.0.0/23?

Answer: 128 subnets and 510 hosts

Question: How many subnets and hosts per subnet can you get from the network 172.26.0.0 255.255.254.0?

Answer: 128 subnets and 510 hosts

Question: What is the last valid host on the subnetwork 192.168.26.164/30?

Answer: 192.168.26.166

Question: What is the broadcast address of the network 172.16.128.64/27?

Answer: 172.16.128.95

Question: What is the last valid host on the subnetwork 172.20.108.0/23?

Answer: 172.20.109.254

Question: What is the broadcast address of the network 192.168.19.64 255.255.255.192?

Answer: 192.168.19.127

Question: How many subnets and hosts per subnet can you get from the network 172.29.0.0/25?

Answer: 512 subnets and 126 hosts

Question: What is the last valid host on the subnetwork 172.26.109.64 255.255.255.192?

Answer: 172.26.109.126

Question: How many subnets and hosts per subnet can you get from the network 172.20.0.0/20?

Answer: 16 subnets and 4094 hosts

Question: What is the last valid host on the subnetwork 172.24.248.0/21?

Answer: 172.24.255.254

Question: You are designing a subnet mask for the 172.20.0.0 network. You want 2400 subnets with up to 8 hosts on each subnet. What subnet mask should you use?

Answer: 255.255.255.240

Question: Which subnet does host 10.156.136.17 255.255.240.0 belong to?

Answer: 10.156.128.0

Question: What is the first valid host on the subnetwork that the node 192.168.247.94 255.255.255.240 belongs to?

Answer: 192.168.247.81

Question: You are designing a subnet mask for the 172.29.0.0 network. You want 900 subnets with up to 50 hosts on each subnet. What subnet mask should you use?

Answer: 255.255.255.192

Question: What is the last valid host on the subnetwork 172.18.192.0 255.255.254.0?

Answer: 172.18.193.254

Question: How many subnets and hosts per subnet can you get from the network 172.18.0.0 255.255.252.0?

Answer: 64 subnets and 1022 hosts

Question: What is the first valid host on the subnetwork that the node 172.31.212.129/26 belongs to?

Answer: 172.31.212.129

Question: What is the first valid host on the subnetwork that the node 172.27.119.100 255.255.255.192 belongs to?

Answer: 172.27.119.65

Question: What is the broadcast address of the network 172.23.54.0 255.255.254.0?

Answer: 172.23.55.255

Question: How many subnets and hosts per subnet can you get from the network 172.30.0.0/27?

Answer: 2048 subnets and 30 hosts

Question: What valid host range is the IP address 172.24.174.81/23 a part of?

Answer: 172.24.174.1 through to 172.24.175.254

Question: What valid host range is the IP address 10.121.14.234 255.255.240.0 a part of?

Answer: 10.121.0.1 through to 10.121.15.254

Question: What valid host range is the IP address 172.30.245.122 255.255.248.0 a part of?

Answer: 172.30.240.1 through to 172.30.247.254

Question: What is the first valid host on the subnetwork that the node 172.27.89.12 255.255.248.0 belongs to?

Answer: 172.27.88.1

Question: What is the first valid host on the subnetwork that the node 172.31.66.156/21 belongs to?

Answer: 172.31.64.1

Question: What is the first valid host on the subnetwork that the node 172.24.76.114 255.255.255.240 belongs to?

Answer: 172.24.76.113

Question: You are designing a subnet mask for the 172.27.0.0 network. You want 120 subnets with up to 400 hosts on each subnet. What subnet mask should you use?

Answer: 255.255.254.0

Question: How many subnets and hosts per subnet can you get from the network 192.168.109.0/29?

Answer: 32 subnets and 6 hosts

Question: You are designing a subnet mask for the 10.0.0.0 network. You want 4000 subnets with up to 3000 hosts on each subnet. What subnet mask should you use?

Answer: 255.255.240.0

Question: What is the first valid host on the subnetwork that the node 172.18.211.242/28 belongs to?

Answer: 172.18.211.241

Question: What is the broadcast address of the network 172.21.58.0/23?

Answer: 172.21.59.255

Question: What is the last valid host on the subnetwork 192.168.174.192 255.255.255.192?

Answer: 192.168.174.254

Question: What is the first valid host on the subnetwork that the node 172.25.186.51 255.255.255.128 belongs to?

Answer: 172.25.186.1

Question: What is the broadcast address of the network 192.168.217.128/26?

Answer: 192.168.217.191

Question: You are designing a subnet mask for the 192.168.104.0 network. You want 15 subnets with up to 8 hosts on each subnet. What subnet mask should you use?

Answer: 255.255.255.240

Question: What valid host range is the IP address 10.206.153.5/20 a part of? Answer: 10.206.144.1 through to 10.206.159.254

Answer: 10.206.144.1 through to 10.206.159.254

Question: Which subnet does host 192.168.199.70/30 belong to? Answer: 192.168.199.68

Answer: 192.168.199.68

Question: What is the last valid host on the subnetwork 172.29.32.0 255.255.254.0?

Answer: 172.29.33.254

Question: What is the broadcast address of the network 10.10.128.0 255.255.240.0?

Answer: 10.10.143.255

Question: What is the broadcast address of the network 172.20.239.0 255.255.255.128?

Answer: 172.20.239.127

Question: What is the first valid host on the subnetwork that the node 172.25.148.179 255.255.255.128 belongs to?

Answer: 172.25.148.129

Question: You are designing a subnet mask for the 10.0.0.0 network. You want 2900 subnets with up to 2200 hosts on each subnet. What subnet mask should you use?

Answer: 255.255.240.0

Question: What valid host range is the IP address 172.21.227.46/25 a part of?

Answer: 172.21.227.1 through to 172.21.227.126

Question: Which subnet does host 10.198.233.93/20 belong to?

Answer: 10.198.224.0

Question: How many subnets and hosts per subnet can you get from the network 172.29.0.0/25?

Answer: 512 subnets and 126 hosts

Question: What is the first valid host on the subnetwork that the node 192.168.182.252/25 belongs to?

Answer: 192.168.182.129

Question: How many subnets and hosts per subnet can you get from the network 192.168.120.0 255.255.255.240?

Answer: 16 subnets and 14 hosts

Question: What is the broadcast address of the network 172.19.168.192 255.255.255.192?

Answer: 172.19.168.255

Question: What valid host range is the IP address 172.18.124.54 255.255.254.0 a part of?

Answer: 172.18.124.1 through to 172.18.125.254

Question: How many subnets and hosts per subnet can you get from the network 172.17.0.0 255.255.255.0?

Answer: 256 subnets and 254 hosts

Question: You are designing a subnet mask for the 172.22.0.0 network. You want 1100 subnets with up to 30 hosts on each subnet. What subnet mask should you use?

Answer: 255.255.255.224

Question: What is the first valid host on the subnetwork that the node 172.16.246.145/22 belongs to?

Answer: 172.16.244.1

Question: Which subnet does host 172.21.74.135 255.255.255.0 belong to?

Answer: 172.21.74.0

Question: Which subnet does host 172.16.27.93/20 belong to?

Answer: 172.16.16.0

Question: What is the last valid host on the subnetwork 172.25.66.0/23?

Answer: 172.25.67.254

Question: What is the last valid host on the subnetwork 172.18.168.0 255.255.248.0?

Answer: 172.18.175.254

Question: What is the last valid host on the subnetwork 172.18.214.0 255.255.254.0?

Answer: 172.18.215.254

Question: What is the first valid host on the subnetwork that the node 192.168.128.61/25 belongs to?

Answer: 192.168.128.1

Question: What is the last valid host on the subnetwork 172.26.154.0 255.255.255.0?

Answer: 172.26.154.254

Question: How many subnets and hosts per subnet can you get from the network 172.29.0.0/26?

Answer: 1024 subnets and 62 hosts

Question: Which subnet does host 192.168.29.219 255.255.255.240 belong to?

Answer: 192.168.29.208

Question: How many subnets and hosts per subnet can you get from the network 172.20.0.0 255.255.240.0?

Answer: 16 subnets and 4094 hosts

Question: What is the broadcast address of the network 10.37.16.0 255.255.240.0?

Answer: 10.37.31.255

Question: What valid host range is the IP address 192.168.145.236/28 a part of?

Answer: 192.168.145.225 through to 192.168.145.238

Question: How many subnets and hosts per subnet can you get from the network 172.19.0.0/22?

Answer: 64 subnets and 1022 hosts

Question: How many subnets and hosts per subnet can you get from the network 172.19.0.0/23?

Answer: 128 subnets and 510 hosts

Question: Which subnet does host 172.27.116.168/23 belong to?

Answer: 172.27.116.0