Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Which statement best explains why a host with a correct IP address but incorrect subnet mask may still fail to communicate properly?
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
Because the host may misidentify local versus remote destinations and choose the wrong forwarding behavior.
This is correct because the subnet mask drives local-versus-remote decisions.
B
Distractor review
Because the subnet mask is used only by switches, not hosts.
This is wrong because hosts absolutely use the subnet mask.
C
Distractor review
Because the mask automatically provides DNS name resolution.
This is wrong because DNS and subnet masks solve different problems.
D
Distractor review
Because the subnet mask replaces the need for a default gateway.
This is wrong because the mask and gateway serve different purposes.
Common exam trap
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Technical deep dive
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
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?
CIDR notation defines the prefix length.
What is the correct answer to this question?
The correct answer is: Because the host may misidentify local versus remote destinations and choose the wrong forwarding behavior. — An incorrect subnet mask breaks the host's ability to distinguish which destinations are local and which are remote. In practical terms, the host may try to ARP for remote destinations that should have gone to the gateway, or it may send local traffic toward the router unnecessarily. That makes normal forwarding decisions unreliable even if the IP address itself looks valid. This is why correct addressing includes both the address and the mask, not just one of them.
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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