Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A host is configured as 172.16.20.190/26. Which range contains the usable host addresses for that subnet?
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
Best answer
172.16.20.129 to 172.16.20.190
This is correct because .128 is the network and .191 is the broadcast.
B
Distractor review
172.16.20.128 to 172.16.20.191
This is wrong because those include the reserved network and broadcast addresses.
C
Distractor review
172.16.20.130 to 172.16.20.191
This is wrong because it excludes one valid host and includes the broadcast address.
D
Distractor review
172.16.20.193 to 172.16.20.254
This is wrong because that range belongs to the next subnet block.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting an answer range that includes the network or broadcast address as usable hosts. For example, option B lists 172.16.20.128 to 172.16.20.191, which incorrectly includes the network (.128) and broadcast (.191) addresses. These addresses are reserved and cannot be assigned to hosts. Another trap is excluding valid host addresses or including addresses from adjacent subnets, as seen in options C and D. Misidentifying subnet boundaries or forgetting to exclude reserved addresses causes these errors, leading to incorrect subnetting answers.
Technical deep dive
How to think about this question
Subnetting divides an IP network into smaller logical segments called subnets, each with its own network address and broadcast address. A /26 subnet mask means the first 26 bits are fixed for the network portion, leaving 6 bits for host addresses. This results in 64 IP addresses per subnet (2^6 = 64), including the network and broadcast addresses. The usable host range excludes these two reserved addresses. To determine the usable host range for a /26 subnet, you identify the subnet block containing the given IP. The blocks increment by 64 in the last octet: 0-63, 64-127, 128-191, and 192-255. Since 172.16.20.190 falls within 128-191, the network address is 172.16.20.128 and the broadcast address is 172.16.20.191. Usable hosts are all addresses between these two, from 172.16.20.129 to 172.16.20.190. A common exam trap is confusing the network and broadcast addresses with usable hosts. Including the network (.128) or broadcast (.191) addresses as usable leads to incorrect answers. Practically, Cisco devices never assign these reserved addresses to hosts. Understanding subnet boundaries and reserved addresses is critical for accurate subnetting and IP planning in CCNA scenarios.
KKey Concepts to Remember
- A /26 subnet mask divides an IP network into blocks of 64 addresses, including network and broadcast addresses.
- The network address is the first IP in the subnet block and cannot be assigned to hosts.
- The broadcast address is the last IP in the subnet block and is reserved for network-wide communication.
- Usable host addresses are all IPs between the network and broadcast addresses within the subnet block.
- Subnet blocks increment by the number of host addresses per subnet, which is 64 for a /26 mask.
- Correct subnetting requires excluding reserved network and broadcast addresses from usable host ranges.
- Misidentifying subnet boundaries or including reserved addresses leads to common exam mistakes.
- Cisco devices never assign network or broadcast addresses to hosts, reinforcing the importance of correct subnetting.
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.
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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 /26 subnet mask divides an IP network into blocks of 64 addresses, including network and broadcast addresses.
What is the correct answer to this question?
The correct answer is: 172.16.20.129 to 172.16.20.190 — A /26 uses blocks of 64 addresses. In practical terms, the fourth-octet ranges are 0–63, 64–127, 128–191, and 192–255. Since 190 falls inside the 128–191 block, the network address is .128 and the broadcast address is .191. That leaves .129 through .190 as the usable range. This is a strong test of whether you can identify the correct block and then exclude the reserved boundary addresses correctly.
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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