Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A host address is 172.16.8.70/26. What is the network address of its 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
Distractor review
172.16.8.0
This is wrong because 70 is not in the 0–63 block.
B
Best answer
172.16.8.64
This is correct because 70 falls within the 64–127 /26 block.
C
Distractor review
172.16.8.70
This is wrong because 70 is the host address, not the network address.
D
Distractor review
172.16.8.128
This is wrong because the 128 block begins above the host address.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is mistaking the host IP address for the network address or selecting the wrong subnet block based on the subnet mask. Candidates often pick 172.16.8.0 because it looks like a common network address or 172.16.8.128 assuming it’s the next block, but these do not contain the host 172.16.8.70 under a /26 mask. The trap arises from not calculating subnet ranges correctly or misunderstanding how subnet masks segment the address space into fixed blocks. This mistake leads to incorrect subnet identification and can cause routing or addressing errors in real networks.
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 subnetworks. Each subnet has a unique network address and a range of host addresses. The subnet mask, expressed in CIDR notation like /26, determines how many bits are used for the network portion versus the host portion of the IP address. In this case, /26 means the first 26 bits are the network part, leaving 6 bits for host addresses, which allows for 64 addresses per subnet. To find the network address of a given host IP with a /26 mask, you identify the subnet block that contains the host. Since each /26 subnet covers 64 addresses, the subnet ranges in the fourth octet are 0–63, 64–127, 128–191, and 192–255. The host address 172.16.8.70 falls within the 64–127 range, so the network address is 172.16.8.64. The network address is always the first address in the subnet block and cannot be assigned to a host. A common exam trap is confusing the host address with the network address or selecting the wrong subnet block. For example, choosing 172.16.8.0 or 172.16.8.128 ignores the actual block boundaries defined by the subnet mask. In practical Cisco networking, correctly identifying subnet boundaries ensures proper routing and IP address management, preventing IP conflicts and routing errors within VLANs or routed interfaces.
KKey Concepts to Remember
- A /26 subnet mask divides the IP address space into blocks of 64 addresses, with 26 bits for the network and 6 bits for hosts.
- The network address is the first IP address in the subnet block and cannot be assigned to a host device.
- Subnet ranges for a /26 mask in the fourth octet are 0–63, 64–127, 128–191, and 192–255, defining distinct subnet boundaries.
- To find the subnet network address, identify which subnet block contains the host IP based on its last octet and subnet mask.
- Incorrectly selecting a subnet block outside the host’s range leads to wrong network addresses and potential routing issues.
- Cisco devices use subnet masks to determine network boundaries, which is critical for routing and IP address management.
- The host IP address itself is never the network address; confusing these leads to common subnetting errors on the CCNA exam.
- Subnetting calculations must be precise to avoid overlapping subnets and ensure proper segmentation in VLANs and routed networks.
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
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Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
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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 the IP address space into blocks of 64 addresses, with 26 bits for the network and 6 bits for hosts.
What is the correct answer to this question?
The correct answer is: 172.16.8.64 — A /26 uses blocks of 64 addresses. In plain language, the fourth-octet subnet ranges are 0–63, 64–127, 128–191, and 192–255. Since the host address ends in 70, it belongs to the 64–127 block. That means the network address of the subnet is 172.16.8.64. This is a standard subnetting calculation. The key is to identify the correct block based on the prefix and then choose the first address in that block as the network address.
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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