Cisco Certified Network Associate (CCNA) 200-301 Practice Test 31
Question 300
A branch routing engineer collects this evidence: An engineer assumes an OSPF path outranks a static path for identical prefixes, despite the installed static route having AD 1 versus OSPF 110. Which root-cause interpretation best fits the observations?
- OSPF always wins over a configured static for the same prefix because it dynamically adapts.
- For identical destination prefixes, default static AD 1 outranks the OSPF route with AD 110 when both are eligible.
- The OSPF route wins because its metric is numerically smaller than the static default distance.
- The chosen route must be the 0/0 default even though a longer matching prefix is installed.
Explanation
Correct Answer
B:Route source administrative distance breaks preference between protocols for the same prefix; lower AD wins. OSPF cost and a static metric cannot be directly compared as if they were one common scale.
Incorrect Answers
A:Dynamism does not override a static AD of 1 versus OSPF AD of 110.
C:AD and protocol metric are distinct values; different protocols’ metrics are not directly comparable.
D:A more-specific destination prefix wins over default for matching traffic.
Question 301
Two OSPFv2 paths to 172.30.50.0/24 are learned in the same area and have equal route type. Path via 10.0.12.2 has total OSPF cost 30; path via 10.0.13.3 has cost 70. Both are reachable and no policy override exists. Which route should the router prefer?
- Both paths must be installed as ECMP because OSPF always balances across unequal costs.
- The path with cost 70, because the larger metric indicates a faster network.
- The path via 10.0.12.2 with cost 30, because OSPF selects the lower cost for otherwise comparable routes.
- The route with the highest numerical next-hop IPv4 address, irrespective of metric.
Explanation
Correct Answer
C:With equal destination prefix length, compatible route type and no policy exception, OSPF chooses the path with the lowest total cost: 30 via 10.0.12.2. The 70-cost alternative does not win merely because it was learned later or has a higher next-hop address. `show ip route 172.30.50.0` reveals the selected OSPF entry, while `show ip ospf interface` and related interface configuration explain contributing cost. If both paths were cost 30 and met equal-cost requirements, ECMP could be considered. Do not compare administrative distance to choose between two routes from the same OSPF source when their costs are the differentiator.
Incorrect Answers
A:Equal-cost multipath requires paths to have equivalent eligible route metrics; a difference between total cost 30 and 70 does not establish an equal-cost set. Cisco OSPF does not generally share traffic across routes with differing costs in the standard ECMP behavior being tested. One path can be retained as an alternate candidate, but both are not necessarily selected into forwarding simply because the prefix and OSPF route type match.
B:OSPF's internal route metric is cumulative path cost. A larger value generally represents a less preferred path, not a faster one. Assuming cost 70 is better reverses the preference rule and would misdiagnose the route selection. Cost is influenced by interface cost and reference bandwidth, which should be checked independently if the actual selected path differs from the design intent.
D:Next-hop address magnitude is not the OSPF path-selection rule. Router IDs and interface priorities are used for other protocol purposes, such as DR election, but sorting next-hop IPv4 addresses does not replace the metric comparison. A correct troubleshooting approach checks route type, administrative distance and total cost, then examines whether candidate paths are actually eligible and reachable. Here the given cost values already identify the preferred path.
Question 302
The router has specific internal routes but no 0.0.0.0/0 and reports the gateway of last resort is not set. The team should investigate which specific technical cause?
- There is no usable IPv4 default route 0.0.0.0/0, so destinations outside installed specific prefixes lack a gateway of last resort.
- The router must route all unknown destinations over any arbitrary connected LAN because a C route exists.
- The router already has a usable default route because the message says gateway of last resort is not set.
- An OSPF neighbor adjacency automatically creates a default route even with no default advertisement or static 0/0.
Explanation
Correct Answer
A:Internal routes enable reachability to their own networks. Unmatched Internet-bound destinations require a suitable default (or other covering route), and its next hop must be reachable.
Incorrect Answers
B:A connected prefix covers only its own subnet, not the global address space.
C:The message explicitly says no active last-resort route exists.
D:OSPF connectivity does not guarantee a default prefix is learned.
Question 303
R1 is configured with ip route 203.0.113.0 255.255.255.0 203.0.113.9. R1 has no independent connected or learned route covering the next-hop address 203.0.113.9. The static route does not appear as an installed usable route. What is the specific routing defect?
- The router is missing an OSPF hello packet from a neighbor on an unrelated VLAN
- The route is rejected because static routes always have lower priority than OSPF routes
- The next-hop address is the same IPv4 address as R1's interface and creates a duplicate IP
- The configured next hop resolves only through the very static prefix being installed, causing self-recursion
Explanation
Correct Answer
D:The configured route claims the whole 203.0.113.0/24 network is reachable through 203.0.113.9, yet that next-hop address is itself inside the same prefix. With no independent connected or learned route to 203.0.113.9, resolving the next hop would require consulting the very static route being installed. This is self-recursive resolution, not a valid route to an output interface. Cisco IOS may withhold a self-recursive static route from its usable RIB. Correct the design by supplying a reachable adjacent next hop or an independently resolvable route, then verify that the static prefix installs without circular lookup.
Incorrect Answers
A:OSPF hellos participate in OSPF neighbor formation, not in the installation of this manually configured static route. The question does not describe an OSPF adjacency as a prerequisite for next-hop reachability. The defect is that no independent path to the configured next-hop IPv4 address exists, so the route would have to refer to itself. Investigate the routing dependency rather than unrelated hello traffic.
B:A normal Cisco static route often has administrative distance 1, whereas an OSPF-learned internal route commonly has administrative distance 110. These values matter only when competing candidates for the same prefix can be installed. Here the configuration cannot be resolved into a valid output path in the first place. It is incorrect to explain this failure by saying static routes always lose to OSPF; they usually win when the same usable prefix is learned by both.
C:The next hop 203.0.113.9 lies inside the destination prefix 203.0.113.0/24, but that does not mean it is configured as a local R1 interface address. No such interface information is supplied. A duplicate IP condition would need separate evidence from interface addressing or duplicate-address behavior. The self-referencing routing dependency is already sufficient to explain why this candidate is unusable.
Question 304
A branch routing engineer collects this evidence: An operator reads 00:04:10 elapsed time and treats it as the route's administrative distance instead of the bracketed [AD/metric] fields. Which root-cause interpretation best fits the observations?
- The first `00` field of `00:04:10` is the route’s administrative distance of zero.
- The route code `O` is an encoding of the line’s age instead of its dynamic routing source.
- The value `20` in `[110/20]` is the route age in hours, and `00:04:10` is the OSPF metric.
- `00:04:10` is a route update age, while bracketed `[110/20]` contains the administrative distance and protocol metric.
Explanation
Correct Answer
D:A routing table line displays distinct fields for source code, prefix, AD/metric, next hop, age and outgoing interface. Changing route preference based on time text confuses aging metadata with a routing decision input.
Incorrect Answers
A:The whole colon-separated field is a duration, not an AD.
B:O identifies OSPF within the table code legend.
C:The bracketed second number is metric; the later duration is elapsed time.
Question 305
The earlier fault was recorded as follows: The address is configured but Gi0/1 is shutdown, so the connected C route is absent from the active routing table. After corrective work, which observation provides direct evidence that the affected function now behaves correctly?
- Gi0/1 still says administratively down while its configured IP address remains in the running configuration.
- The router learned a remote OSPF prefix while the Gi0/1 C route remains missing.
- The switch’s VLAN database contains the correct VLAN name but Gi0/1 stays down/down.
- Gi0/1 is no longer shutdown and is up/up; `show ip route connected` includes its correct C subnet and an L /32 for its interface address.
Explanation
Correct Answer
D:The reported defect was a connected route absent due to shutdown. Restoring operational L3 interface state makes both on-link and local address entries active; a configuration line alone is insufficient.
Incorrect Answers
A:Administrative shutdown prevents the intended active connected route from reappearing.
B:A separate OSPF route does not demonstrate this connected interface recovered.
C:A VLAN label elsewhere is not an acceptance check for the router’s L3 connected route.
Question 306
A branch routing engineer has repaired a network problem. A technician confuses the L /32 entry with the connected C /24 subnet and expects packets to the interface IP to be routed onward. Which device or protocol check is the strongest evidence that this particular failure is gone?
- `L /32` appears for every random host in the /24 simply because the C subnet exists.
- Packets to the router’s interface IP use an OSPF next hop as though the router does not own that address.
- `show ip route <interface-IP>` selects `L <address>/32`, while a different host in the same /24 matches its `C <subnet>/24` route.
- The C subnet is absent whenever an L /32 is present on a normal up/up numbered interface.
Explanation
Correct Answer
C:The correct comparison shows two different forwarding semantics: exact router-owned destination versus an on-link neighboring host. The local /32 wins the longest-match check for the router IP.
Incorrect Answers
A:L entries represent configured local interface addresses, not the entire on-link host population.
B:The L /32 entry directs locally addressed packets to the router itself.
D:IOS routinely installs both connected subnet and local host entries.
Question 307
A network acceptance test follows this reported failure: The configured next hop has no independent route, so the configured S destination never becomes a usable installed route. Which verification most specifically demonstrates the repaired function rather than checking an unrelated feature?
- The static command is still in running-config, but the S destination is absent from the active routing table.
- A DNS hostname resolves while the static next hop still has no route in the RIB.
- `show ip interface brief` lists an unrelated up interface while the S route remains unresolved.
- `show ip route static` now contains the target S prefix via a resolvable next hop; `show ip route <next-hop>` identifies an active egress interface.
Explanation
Correct Answer
D:The failure involved a configured static that could not recurse to an outgoing adjacency. Verifying both installed S route and usable resolution proves the specific forwarding prerequisite.
Incorrect Answers
A:Configured text was already present during the fault and did not make the route usable.
B:DNS does not establish recursive IP forwarding resolution to the next hop.
C:Another link’s state does not prove the desired next-hop route is installed.
Question 308
A branch routing engineer is validating a repair. Earlier, the expected O route is absent because the transit interface is passive and never establishes a neighboring adjacency. Which postchange check most directly establishes the specific problem is resolved?
- The transit interface remains passive with no neighbor, but an unrelated connected route exists.
- Only the local OSPF router ID is visible while the neighbor state is Down.
- After removing passive from the OSPF transit interface, `show ip ospf neighbor` shows the expected Full adjacency and `show ip route` installs the intended O prefix.
- A default route exists but the targeted remote OSPF prefix remains absent.
Explanation
Correct Answer
C:A passive OSPF interface advertises its network but does not send OSPF hellos to form neighbors. Restoring an active transit session and receiving the route verifies both control and data-plane outcomes.
Incorrect Answers
A:A connected route cannot prove the absent OSPF adjacency and remote O prefix are restored.
B:A valid router ID does not make passive transit hello exchange work.
D:A 0/0 route does not demonstrate recovery of the exact intra-area learned prefix.
Question 309
A router now has active 198.51.100.0/24 via R2 and 0/0 via R3. A packet from 10.0.0.10 to 198.51.100.18 arrives without policy-based routing. Which lookup outcome confirms normal forwarding?
- The route for source subnet 10.0.0.0/24 is selected despite the destination matching 198.51.100.0/24.
- The 0/0 next hop is always preferred over the matching 198.51.100.0/24 entry.
- `show ip route 198.51.100.18` resolves to the installed 198.51.100.0/24 next hop via R2, independent of the packet source without PBR.
- The route is selected by an unrelated inbound SSH ACL rather than the destination RIB/FIB.
Explanation
Correct Answer
C:This explicitly tests the destination-based longest-prefix match. A proper FIB lookup should not choose a route for the source subnet when forwarding to 198.51.100.18.
Incorrect Answers
A:That would confuse normal forwarding source with destination.
B:A /24 is more specific than the default.
D:Ordinary packet forwarding does not derive the next hop from an administrative SSH ACL.
Question 310
A branch routing engineer has repaired a network problem. A packet for 192.0.2.200 was assumed to match 192.0.2.0/25, but that destination actually lies in the other /25. Which device or protocol check is the strongest evidence that this particular failure is gone?
- Treat 192.0.2.0/25 as covering .200 because it shares the first 24 bits.
- Interpret 192.0.2.128/25 as ending at .191 and therefore excluding .200.
- `show ip route 192.0.2.200` matches 192.0.2.128/25 (if installed), not 192.0.2.0/25; the boundary is .128.
- Expect the /32 local route for 192.0.2.1 to match every 192.0.2.x destination.
Explanation
Correct Answer
C:The destination .200 has high bit 1 in the final octet. Comparing prefixes with /25 mask 255.255.255.128 places it in the upper /25. If no upper /25 exists, a less-specific installed route may be used.
Incorrect Answers
A:The /25 requires a match in the 25th bit, which differs for .200.
B:A /25 block includes .128–.255, not only the first /26.
D:A /32 only matches that exact local IP.
