Cisco Certified Network Associate (CCNA) 200-301 Practice Test 35
Question 340
R1 learns 10.30.0.0/16 through OSPF (AD 110). A backup static for that SAME /16 uses AD 200 and is configured correctly; only the OSPF entry appears in the active table. Why is the backup not forwarding traffic now?
- The static route should win because 200 is numerically greater than 110.
- The backup is broken because every configured static route must appear as an active forwarding entry.
- The OSPF route has lower administrative distance and correctly remains active until it is withdrawn or becomes unusable.
- The default route takes priority over both entries regardless of their masks.
Explanation
Correct Answer
C:For identical destination prefixes, route installation normally prefers the source with the lower administrative distance. A floating static with AD 200 deliberately waits behind the OSPF path of AD 110.
Incorrect Answers
A:Administrative distance is a lower-is-better preference, not a priority score where a higher number wins.
B:A configured floating static is expected to be absent from the active RIB while a preferred, usable route to the same prefix exists.
D:An installed specific /16 path is more specific than a default and remains the applicable forwarding route for destinations inside its range.
Question 341
Troubleshooting report: Only one host is unreachable despite healthy /24 routing because its installed /32 Null0 route discards every matching packet. Which finding best accounts for the behavior?
- An installed static host-specific /32 route to Null0 matches exactly the failed host and discards it ahead of the healthy covering /24.
- The whole /24 should fail equally because any /32 Null0 route blocks all addresses in the /24.
- A lower-AD /24 always beats a /32 regardless of prefix length.
- Null0 is an alias for the OSPF default route and forwards packets to the next available neighbor.
Explanation
Correct Answer
A:With longest-prefix lookup, the /32 wins for its one address; the /24 still routes neighboring hosts. Fix the accidental discard host route rather than rebuilding all subnet routes.
Incorrect Answers
B:A /32 selects one exact host; other destinations can use the existing /24.
C:AD is not compared across different destination prefix lengths before longest match.
D:Null0 is a packet-discard interface.
Question 342
An audit found a claim that packets for 10.30.40.99 should use 10.30.0.0/16 despite a reachable installed 10.30.40.0/24. No PBR is configured. Which observation confirms the forwarding decision is correct?
- Select 10.30.0.0/16 solely because its administrative distance is lower than the /24 route.
- Select default 0/0 because both installed prefixes are valid.
- Use the source host’s subnet to choose the outgoing interface and ignore destination 10.30.40.99.
- A destination lookup for 10.30.40.99 selects active 10.30.40.0/24 ahead of the broader 10.30.0.0/16, and a forwarding test follows that /24 next hop.
Explanation
Correct Answer
D:The /24 matches more leading destination bits than /16 and is eligible, so ordinary forwarding must choose it. A claim to use /16 should prompt checking the actual RIB/FIB or policy-based routing.
Incorrect Answers
A:Longest-prefix matching selects the /24 before comparing AD for different prefixes.
B:Both a /16 and /24 are more specific than default; /24 matches best.
C:Without PBR, ordinary FIB lookup uses destination address.
Question 343
A network acceptance test follows this reported failure: A single host 192.0.2.88 blackholes through an installed /32 next hop while neighboring hosts in 192.0.2.0/24 work. Which verification most specifically demonstrates the repaired function rather than checking an unrelated feature?
- `show ip route 192.0.2.88` now selects the repaired /32 next hop instead of the former blackhole, and a packet test to .88 succeeds.
- The neighboring host 192.0.2.89 reaches its gateway while .88 still matches the bad /32.
- The 192.0.2.0/24 remains present, while the erroneous /32 route still wins for .88.
- The router has a usable 0/0 route, but .88 still follows the bad /32.
Explanation
Correct Answer
A:The original /32 was a more-specific bad route affecting one host. Test the exact destination lookup and forwarding; neighboring hosts working through /24 is not enough.
Incorrect Answers
B:Another /24 address did not have the targeted /32 problem.
C:A healthy covering subnet route cannot override the incorrect more-specific host route.
D:Default is least specific and cannot supersede the bad /32 for that host.
Question 344
A branch routing engineer is validating a repair. Earlier, traffic to 192.0.2.50 goes via the /24, while 192.0.2.180 uses the more-specific /25; an engineer expects both to take /25. Which postchange check most directly establishes the specific problem is resolved?
- Both .50 and .180 should use the upper /25 solely because it has a longer mask.
- Both addresses should use default 0/0 because the /24 is a connected supernet.
- Address 192.0.2.180 lies in the first /25 ending .127.
- Route lookups show 192.0.2.50 matches installed /24, whereas 192.0.2.180 matches installed upper-half 192.0.2.128/25.
Explanation
Correct Answer
D:The two destinations occupy opposite /25 halves. A /25 upper block cannot match .50, so the broader /24 handles that host if no more-specific lower-half route exists.
Incorrect Answers
A:A longer prefix must also match each destination; .50 lies outside .128/25.
B:The installed /24 and /25 are more specific matching candidates than default.
C:The /25 high-half range is .128–.255.
Question 345
The earlier fault was recorded as follows: A route switched to OSPF after someone raised the static route's administrative distance above 110 while keeping the prefix unchanged. After corrective work, which observation provides direct evidence that the affected function now behaves correctly?
- Assume a static route always wins even when explicitly configured with AD 200 and OSPF AD 110 is eligible.
- The RIB’s installed next hop for the identical prefix now agrees with the intended AD policy: the static wins only if its configured AD is lower than 110, otherwise OSPF wins.
- Judge preference from OSPF route age alone without inspecting AD.
- Compare static metric zero to OSPF metric 10 while ignoring the changed static AD.
Explanation
Correct Answer
B:An administrator changed static route AD above OSPF’s 110, reversing the preference. The acceptance check must read the actual configured AD and installed winner, not assert that static always takes precedence.
Incorrect Answers
A:An intentionally floating static has a higher distance and is suppressed behind the OSPF route.
C:Age does not determine route-source preference for the same prefix.
D:Administrative distance decides between route sources before protocol metrics can be compared.
Question 346
A branch routing engineer has repaired a network problem. An engineer reads a lower OSPF route metric and expects it to defeat an internal EIGRP path despite the protocol AD difference. Which device or protocol check is the strongest evidence that this particular failure is gone?
- The active route for the same prefix shows internal EIGRP AD 90 rather than OSPF AD 110, regardless of numerically lower OSPF cost.
- Choose OSPF cost 10 over EIGRP AD 90 because 10 is the smaller number.
- Use the route age field instead of `[AD/metric]` to choose between protocols.
- Prefer any default 0/0 over a matching installed prefix because it is the gateway of last resort.
Explanation
Correct Answer
A:For eligible equal-prefix paths from different protocols, default AD 90 (internal EIGRP) is preferred to OSPF 110. Cross-protocol path metrics use unrelated algorithms and should not be compared as universal scores.
Incorrect Answers
B:The two fields are metric and administrative distance, not comparable measures of the same thing.
C:Route age tracks update time, not administrative source trust.
D:A more-specific route to the destination outranks default.
Question 347
A network acceptance test follows this reported failure: show ip route contains two next hops for one OSPF prefix; a technician incorrectly calls this duplicate-entry corruption. Which verification most specifically demonstrates the repaired function rather than checking an unrelated feature?
- Delete one next hop solely because a routing table must contain exactly one next hop per prefix.
- Read only the OSPF router ID while never checking routes or next-hop usability.
- `show ip route <prefix>` lists two valid equal-cost OSPF next hops with the expected cost, and flow forwarding distributes over eligible paths without loops.
- Treat packets reaching the destination by either link as proof of a loop, without observing repeated circulation.
Explanation
Correct Answer
C:More than one next hop can be a valid ECMP installation. Verify both paths are usable and their origin/metrics rather than counting them as corrupt duplicates.
Incorrect Answers
A:ECMP legitimately allows multiple next hops for the same network.
B:Router identity does not prove the installed ECMP forwarding set is correct.
D:Load sharing is not itself a routing loop.
Question 348
A branch routing engineer is validating a repair. Earlier, after an uplink disappears, its next hop becomes unreachable; show ip route withdraws that specific static while other paths remain. Which postchange check most directly establishes the specific problem is resolved?
- After the primary uplink is removed, the unresolved static is absent from the active RIB and the expected eligible backup route (if present) is selected.
- The static command remains in running-config and is assumed to forward through the down uplink.
- A local L /32 route to the router’s own interface still exists, so the remote static is declared recovered.
- A new default route exists but route lookup to the original destination still chooses a broken specific static.
Explanation
Correct Answer
A:A next-hop-dependent static should withdraw when it cannot resolve, allowing alternate routes to serve the same destination. Verify by destination lookup and controlled failover, not by configuration text.
Incorrect Answers
B:A configured static with unresolved next hop is not an active usable route.
C:Local interface reachability cannot establish resolution of the remote static next hop.
D:Forwarding must actually choose a usable path after the link loss.
Question 349
R1 has active routes for 192.0.2.0/24 and a default route `S* 0.0.0.0/0 via 203.0.113.1`. A client at 192.0.2.10 sends a packet to 8.8.8.8, which matches no more-specific route. Which test establishes the real forwarding next hop, beyond merely seeing a default entry in the RIB?
- Inspect only an IPv6 route for 2001:db8::/32.
- Run a CEF exact-route/forwarding lookup for source 192.0.2.10 and destination 8.8.8.8 and confirm the outgoing next hop is 203.0.113.1.
- Compare the OSPF costs of unrelated local prefixes without checking the packet destination.
- Check whether an unused 10.100.0.0/16 summary is directed to Null0.
Explanation
Correct Answer
B:An IPv4 CEF forwarding or exact-route lookup evaluates the given flow against the installed forwarding entries and identifies the egress next hop. Since 8.8.8.8 matches no longer prefix, it should resolve via the default to 203.0.113.1; this verifies packet disposition, not merely route presence.
Incorrect Answers
A:An IPv6 route does not describe how an IPv4 packet addressed to 8.8.8.8 is forwarded. The requested test must use the IPv4 FIB and its actual egress information.
C:OSPF metrics are relevant to comparable OSPF paths, but unrelated prefix costs cannot establish forwarding for an unmatched Internet destination using a static default.
D:A Null0 summary for another destination does not match 8.8.8.8 and cannot prove how the default route forwards that packet. Longest-prefix selection must be evaluated with the actual destination.
Question 350
An IPv6 router has an installed unicast route `2001:db8:100:50::/64` via the on-link next hop `fe80::2` on Gi0/1. `show ipv6 route` displays the correct prefix, but packets to 2001:db8:100:50::99 are dropped. The router has sent repeated Neighbor Solicitations for `fe80::2` and receives no Neighbor Advertisement. Which verification isolates the forwarding failure?
- Check `show ipv6 neighbors` for the Gi0/1 next-hop `fe80::2`, verify the neighbor/adjacency is unresolved, and restore on-link NDP reachability before expecting the installed route to forward packets.
- Prefer any less-specific installed /48 route automatically because an unresolved NDP entry changes the destination longest-prefix rule.
- Use an IPv4 ARP cache entry for 192.0.2.2 to complete the IPv6 `fe80::2` adjacency.
- Change the DNS A record of the destination to a different IPv4 address, without checking Neighbor Solicitations.
Explanation
Correct Answer
A:The route is present in the IPv6 routing table, but a Layer 3 next-hop on an Ethernet link still needs a link-layer neighbor mapping. IPv6 Neighbor Discovery sends solicitations to resolve and verify neighbors. With no advertisements, the forwarding adjacency stays incomplete; prefix selection alone is not sufficient for packet delivery.
Incorrect Answers
B:The routing lookup still selects the most specific matching installed route; a failed neighbor resolution affects adjacency/forwarding, not prefix ordering.
C:IPv6 uses ICMPv6 Neighbor Discovery rather than IPv4 ARP to map IPv6 next hops.
D:The observed traffic already uses an IPv6 literal and fails at the IPv6 next-hop adjacency.
