Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A host address is 10.77.4.141/28. Which address is the network address of the 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
10.77.4.128
This is correct because .141 is in the 128-143 /28 subnet.
B
Distractor review
10.77.4.143
This is wrong because .143 is the broadcast address of the subnet.
C
Distractor review
10.77.4.144
This is wrong because .144 starts the next /28 subnet.
D
Distractor review
10.77.4.112
This is wrong because .112 belongs to an earlier /28 block.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is confusing the broadcast address with the network address. For a /28 subnet, the broadcast address is the last IP in the block, not the first. Selecting 10.77.4.143 might seem correct because it’s close to the host IP, but it is actually the broadcast address. Always calculate the subnet range carefully before choosing.
Technical deep dive
How to think about this question
A /28 subnet mask corresponds to 255.255.255.240, which means 28 bits are fixed for the network and 4 bits are left for host addressing. The block size is calculated as 256 minus the last octet of the subnet mask (256 - 240 = 16). This divides the IP address space into subnets with 16 addresses each. The network address is the first IP in the block, the broadcast address is the last IP, and the usable hosts are the IPs in between. For the IP 10.77.4.141/28, you determine the subnet by finding which 16-address block contains 141. Since 128 to 143 is one such block, 10.77.4.128 is the network address, 10.77.4.143 is the broadcast, and 10.77.4.129 through 10.77.4.142 are usable host addresses. Understanding this calculation is crucial for subnetting questions on the CCNA exam.
KKey Concepts to Remember
- /28 subnet mask equals 255.255.255.240
- Subnet block size is 16 addresses
- Network address is the first IP in the subnet block
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?
/28 subnet mask equals 255.255.255.240
What is the correct answer to this question?
The correct answer is: 10.77.4.128 — A /28 subnet has a block size of 16. In practical terms, the last-octet blocks are 0-15, 16-31, 32-47, and so on. Because 141 falls within the 128-143 block, the network address is 10.77.4.128. This is a clean addressing-boundary question that rewards careful block calculation rather than guesswork.
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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