Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A host is configured as 10.20.30.95/27. Which address 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
10.20.30.32
This is wrong because .95 is not in the 32–63 block.
B
Best answer
10.20.30.64
This is correct because the host falls within the 64–95 /27 block.
C
Distractor review
10.20.30.95
This is wrong because .95 is the host address, not the network address.
D
Distractor review
10.20.30.96
This is wrong because .96 is the beginning of the next /27 block.
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 incorrectly identifying the subnet block boundaries. Candidates often select the host IP itself or the next block's starting address as the network address. For example, choosing 10.20.30.95 or 10.20.30.96 instead of 10.20.30.64. This happens because the subnet mask’s block size (32 addresses for /27) is overlooked, leading to confusion about which block the host belongs to. Misunderstanding this can cause incorrect subnetting and routing errors in real networks.
Technical deep dive
How to think about this question
Subnetting divides a larger IP network into smaller, manageable subnetworks by borrowing bits from the host portion of the IP address to create subnet bits. A /27 subnet mask means 27 bits are fixed for the network and subnet combined, leaving 5 bits for host addressing. This results in subnet blocks of 32 IP addresses each (2^5 = 32), where the first address is the network address, the last is the broadcast address, and the addresses in between are usable host addresses. To determine the network address for a host IP with a /27 mask, identify which 32-address block the host falls into. The blocks start at multiples of 32 in the last octet: 0, 32, 64, 96, etc. Since the host IP is 10.20.30.95, it falls within the 64–95 range. The network address is the first address in this block, 10.20.30.64, which represents the subnet's identifier for routing and addressing purposes. A common exam trap is confusing the host address with the network address or miscalculating subnet boundaries by not correctly applying the subnet mask. For example, selecting 10.20.30.95 as the network address is incorrect because it is a host address. Similarly, choosing 10.20.30.96 is wrong because it belongs to the next subnet block. Understanding the subnet block ranges and their boundaries is critical for accurate subnetting and avoiding misconfiguration in Cisco networks.
KKey Concepts to Remember
- A /27 subnet mask uses 27 bits for network and subnet, leaving 5 bits for host addresses, creating subnet blocks of 32 IP addresses each.
- The network address is always the first IP address in the subnet block and identifies the subnet uniquely in routing.
- Subnet blocks increment in multiples of the block size, which is 32 for a /27 mask, starting at 0, 32, 64, 96, and so on in the last octet.
- The host IP address must fall within the subnet block range, excluding the network and broadcast addresses.
- Choosing the host IP or the next block’s starting IP as the network address is a common mistake that leads to subnetting errors.
- Cisco devices use the network address to route packets correctly within and between subnets.
- Understanding subnet boundaries is essential for configuring IP addressing and avoiding address overlap or misrouting.
- Subnetting requires precise calculation of block ranges to ensure proper network segmentation and efficient IP address utilization.
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 /27 subnet mask uses 27 bits for network and subnet, leaving 5 bits for host addresses, creating subnet blocks of 32 IP addresses each.
What is the correct answer to this question?
The correct answer is: 10.20.30.64 — A /27 uses blocks of 32 addresses. In plain language, the ranges in the last octet are 0–31, 32–63, 64–95, 96–127, and so on. Since the host address ends in 95, it belongs to the 64–95 block. The first address in that block is the network address, which is 10.20.30.64. This is a classic subnet-boundary question because it tests whether you can identify the containing block 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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