Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A routing table contains these entries for the same destination space: 10.1.0.0/16, 10.1.10.0/24, and 0.0.0.0/0. Which route is used for traffic to 10.1.10.44?
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
10.1.0.0/16
This is wrong because the /16 is less specific than the matching /24 route.
B
Best answer
10.1.10.0/24
This is correct because 10.1.10.44 falls within that more specific prefix.
C
Distractor review
0.0.0.0/0
This is wrong because the default route is used only when no more specific route matches.
D
Distractor review
No route, because the entries overlap
This is wrong because overlapping routes are normal and longest-prefix match resolves the decision.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting the less specific route (10.1.0.0/16) or the default route (0.0.0.0/0) for the destination 10.1.10.44. Candidates might mistakenly believe that overlapping routes cause conflicts or that the default route overrides specific routes. However, Cisco routers always apply the longest-prefix match rule, choosing the most specific subnet mask that fits the destination IP. Overlapping routes do not cause routing failures; instead, they provide multiple options where the router picks the best match. Misunderstanding this can lead to incorrect answers and confusion about routing behavior.
Technical deep dive
How to think about this question
Routing tables store multiple routes to various destination networks, each identified by a network prefix and subnet mask. When a router receives a packet, it uses the destination IP address to find the best matching route in its routing table. The core principle governing this selection is the longest-prefix match rule, which means the router chooses the route with the most specific subnet mask that matches the destination IP address. In this question, the routing table contains three entries: 10.1.0.0/16, 10.1.10.0/24, and 0.0.0.0/0. The destination IP 10.1.10.44 falls within both the /16 and /24 subnets, but the /24 prefix is more specific because it has a longer subnet mask (24 bits vs. 16 bits). Therefore, the router selects the 10.1.10.0/24 route for forwarding the packet. The default route 0.0.0.0/0 is only used if no other more specific route matches the destination. A common exam trap involves misunderstanding overlapping routes and default routes. Overlapping routes are normal in routing tables, and the router always prefers the longest-prefix match. The default route serves as a catch-all for unknown destinations and is not preferred over any specific route. In practical networking, this behavior ensures efficient routing by directing traffic to the most precise path available, reducing unnecessary hops and improving network performance.
KKey Concepts to Remember
- A router uses the longest-prefix match rule to select the most specific route that matches the destination IP address in its routing table.
- Routes with longer subnet masks (higher prefix lengths) are preferred over less specific routes when forwarding traffic.
- The default route 0.0.0.0/0 is only used when no other more specific route matches the destination IP address.
- Overlapping routes in a routing table are normal and do not cause routing conflicts; the router resolves them by prefix specificity.
- Cisco routers compare destination IP addresses against all routes and install the route with the highest prefix length in the forwarding table.
- A less specific route like 10.1.0.0/16 covers a broader range of addresses but is overridden by any more specific route like 10.1.10.0/24.
- Routing decisions are based on prefix length first, then administrative distance and metric if multiple routes have the same prefix length.
- Understanding subnetting and prefix lengths is essential for correctly interpreting routing table entries and route selection.
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
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.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
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 router uses the longest-prefix match rule to select the most specific route that matches the destination IP address in its routing table.
What is the correct answer to this question?
The correct answer is: 10.1.10.0/24 — The 10.1.10.0/24 route is used because it is the most specific matching prefix. In plain language, even though the /16 route and the default route could also match, the /24 route describes the destination range more precisely. Longest-prefix match therefore selects the /24 entry. This is a foundational route-selection rule. The default route remains important as a fallback, but it is not used when more specific routes exist. Likewise, the /16 route is less specific than the /24, so it loses for this destination.
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.
Discussion
Loading comments…
Sign in to join the discussion.