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hardmultiple choiceObjective-mapped

A subnet uses the prefix /22. How many usable host addresses are available?

Answer choices

Why each option matters

Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.

A

Distractor review

254

This is wrong because 254 usable hosts corresponds to a /24.

B

Distractor review

510

This is wrong because 510 usable hosts corresponds to a /23.

C

Best answer

1022

This is correct because a /22 has 1024 total addresses and 1022 usable hosts.

D

Distractor review

2046

This is wrong because 2046 usable hosts corresponds to a /21.

Common exam trap

Common exam trap: answer the scenario, not the keyword

A frequent exam trap is selecting the total number of IP addresses in the subnet instead of the usable host count. Candidates often mistake the 1024 total addresses in a /22 subnet as usable hosts, forgetting to subtract the network and broadcast addresses. Another common error is confusing the prefix length with similar ones like /23 or /21, which have different host capacities. This confusion leads to selecting options like 510 or 2046 usable hosts, which correspond to /23 and /21 respectively, not /22. Understanding the difference between total and usable addresses is essential to avoid this pitfall.

Technical deep dive

How to think about this question

Subnetting is a fundamental concept in IP networking that divides a larger network into smaller, manageable segments called subnets. The prefix length, such as /22, indicates how many bits are used for the network portion of the address, with the remaining bits allocated for host addresses. In IPv4, an address is 32 bits long, so a /22 prefix means 22 bits are fixed for the network, leaving 10 bits for host addressing. The number of usable host addresses in a subnet is calculated by taking 2 to the power of the number of host bits and subtracting 2 addresses reserved for network and broadcast. For a /22 subnet, 32 - 22 = 10 host bits, so 2^10 = 1024 total addresses. Subtracting 2 reserved addresses results in 1022 usable host addresses. This calculation is critical for Cisco CCNA candidates to understand subnet capacity and address planning. A common exam trap is confusing the total number of addresses with usable hosts or mixing up prefix lengths. For example, a /24 subnet has 256 total addresses but only 254 usable hosts. Misreading the prefix or forgetting to subtract the network and broadcast addresses leads to incorrect answers. In practical Cisco networking, accurate subnetting ensures efficient IP address allocation and prevents address conflicts or wasted space.

KKey Concepts to Remember

  • A subnet prefix length determines how many bits are allocated for the network versus host portions of an IPv4 address.
  • The number of usable host addresses in a subnet equals 2 to the power of host bits minus 2 reserved addresses for network and broadcast.
  • A /22 subnet has 10 host bits, resulting in 1024 total addresses and 1022 usable host addresses after subtracting reserved addresses.
  • Network and broadcast addresses are always reserved and cannot be assigned to hosts within a subnet.
  • Confusing total IP addresses with usable host addresses is a common mistake in subnetting calculations.
  • Subnetting calculations are essential for efficient IP address allocation and avoiding address conflicts in Cisco networks.
  • Understanding how to calculate usable hosts from prefix length is critical for CCNA exam success in network fundamentals.
  • Incorrectly matching prefix lengths to host counts leads to common exam traps and wrong answer choices.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Related practice questions

Related 200-301 practice-question pages

Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.

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CCNA IPv6 practice questions

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More questions from this exam

Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.

Question 1

A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?

Question 2

A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?

Question 3

What is the OSPF metric called?

Question 4

A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?

Question 5

A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?

Question 6

A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?

FAQ

Questions learners often ask

What does this 200-301 question test?

A subnet prefix length determines how many bits are allocated for the network versus host portions of an IPv4 address.

What is the correct answer to this question?

The correct answer is: 1022 — A /22 leaves 10 host bits available. In plain language, that means each subnet contains 2^10, or 1024, total addresses. Two of those are reserved for the network and broadcast addresses in normal IPv4 subnetting, leaving 1022 usable host addresses. This is a common subnet-capacity calculation. The safest method is to calculate the total address count from the number of host bits and then subtract the two reserved addresses. That leads directly to the correct usable-host value.

What should I do if I get this 200-301 question wrong?

Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.

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