Cisco Certified Network Associate (CCNA) 200-301 Practice Test 30
Question 290
A branch router has installed connected 10.8.0.0/24, static 172.16.8.0/24, and OSPF 192.168.20.0/24 routes. Host 198.51.100.80 matches none of them. Which additional route would allow the router to select an upstream next hop for such otherwise unmatched IPv4 destinations?
- An installed 0.0.0.0/0 default route with a reachable upstream next hop.
- An added local 10.8.0.1/32 route for the branch router's own interface.
- A static 172.16.8.0/24 route with an even lower administrative distance.
- A route to 192.168.20.0/25 learned through OSPF.
Explanation
Correct Answer
A:A default route has prefix length zero, so it matches destinations when no longer-prefix entry matches. An installed 0.0.0.0/0 route with a valid next hop provides the branch router's gateway of last resort for 198.51.100.80 and other unmatched destinations. The router still needs a resolved next hop and working upstream forwarding, so merely entering a command does not guarantee Internet reachability. Verify `show ip route 0.0.0.0` and test the next hop before claiming full service. Specific connected, static or OSPF routes take priority for destinations they cover because they are longer matches; the default does not replace those entries. This is the defining role of gateway of last resort in IPv4 routing.
Incorrect Answers
B:A local /32 identifies a particular IP address assigned to the router itself. It does not supply a path to arbitrary remote destinations such as 198.51.100.80. Even though a local host route is a very specific entry, it does not match an unrelated address. A route must contain the destination to be eligible for forwarding selection, so adding another local address record is irrelevant.
C:Administrative distance influences which competing route source is installed for the same prefix, but it does not expand a 172.16.8.0/24 route to cover 198.51.100.80. That address lies in a different network. Reducing the distance of a nonmatching route cannot make it a gateway of last resort. Prefix membership is the first question to ask.
D:A /25 route within 192.168.20.0/24 describes an even narrower destination subset of that already installed network. It matches only addresses in the covered half of 192.168.20.x and cannot provide a path for 198.51.100.80. Changing routing protocol does not alter the destination network described by the prefix. The unmatched host needs a default or other matching route.
Question 291
R1 has `S 10.70.0.0/16 via 198.51.100.9`. It also has `S 198.51.100.9/32 via 192.0.2.2` and a connected 192.0.2.0/30 on Gi0/1. There is no self-recursion. Which forwarding resolution correctly describes how R1 reaches the destination 10.70.4.8?
- The destination is unresolved because every static next-hop address must be on a directly connected subnet.
- R1 sends directly toward 10.70.4.8 by ARPing for that remote host on Gi0/1.
- R1 chooses a default route because the first route names an intermediate next-hop.
- R1 resolves 198.51.100.9 through 192.0.2.2, which belongs to the connected /30 on Gi0/1, and forwards there.
Explanation
Correct Answer
D:The first static sends the packet toward 198.51.100.9, the second resolves that intermediate next hop through 192.0.2.2, and 192.0.2.0/30 supplies the final connected Ethernet interface Gi0/1. This is valid bounded recursive forwarding with an independently reachable final adjacency.
Incorrect Answers
A:Recursive next-hop resolution is permitted: an intermediate route can identify how to reach the configured next hop. The process fails only if there is no usable independent resolution or a recursion loop.
B:R1 needs a Layer 2 adjacency for the resolved on-link next hop 192.0.2.2, not a MAC for distant 10.70.4.8. The destination stays in the IP route lookup and is not ARPed as if locally connected.
C:The explicit 10.70.0.0/16 static is more specific than a default route, and it is usable because its next hop recursively resolves. Default is not selected merely because recursion has multiple steps.
Question 292
A branch routing engineer must implement a change. A show ip route line includes an elapsed-time field after the protocol, next-hop and metric; time is not AD. Which technical decision most directly meets these requirements?
- Treat `00:04:10` as administrative distance 4 and OSPF cost 10.
- The `00:04:10` field reports approximately four minutes since the route was updated; `[110/20]` separately gives OSPF AD 110 and metric 20.
- Treat the code `O` as seconds since route installation instead of the OSPF protocol identifier.
- Treat the route age as the IPv4 subnet mask length and omit the printed `/24` prefix.
Explanation
Correct Answer
B:In a typical `show ip route` next-hop line, the bracketed distance/metric pair and the later elapsed age serve different purposes. An age timestamp should not be parsed as path preference.
Incorrect Answers
A:The time-shaped field is age; the bracketed values carry routing preference fields.
C:O is the intra-area OSPF route code in an IOS routing table.
D:Prefix length is specified in the destination route, not encoded by a duration string.
Question 293
Troubleshooting report: The address is configured but Gi0/1 is shutdown, so the connected C route is absent from the active routing table. Which finding best accounts for the behavior?
- The Gi0/1 shutdown prevents its connected subnet and local host route from being active in the RIB; restore the interface to an operational up/up state.
- The connected C route must remain active while Gi0/1 is administratively shutdown because its IP address is configured.
- An unrelated switch’s missing DHCP DNS option always removes connected routes from the router.
- The missing route proves an OSPF neighbor’s administrative distance changed from 110 to 120.
Explanation
Correct Answer
A:Connected routes depend on the relevant L3 interface being enabled and operational. An IP address retained in running-config on a shutdown interface does not guarantee installed C or L routes.
Incorrect Answers
B:Installed connected routes require usable interface state.
C:A router interface’s C route is derived from local addressing/link state rather than a remote host DNS option.
D:This is a directly connected route absent because of shutdown, not an OSPF learned-route preference dispute.
Question 294
A technician confuses the L /32 entry with the connected C /24 subnet and expects packets to the interface IP to be routed onward. The team should investigate which specific technical cause?
- Both L /32 and C /24 entries mean every packet to the router’s own IP must be forwarded to the far host.
- The L code identifies an OSPF LSA that can only be installed after adjacency formation.
- A connected C /24 can never coexist with an L /32 on the same numbered interface.
- The `L <interface-IP>/32` route means the router itself owns that exact destination; `C <subnet>` covers on-link peers.
Explanation
Correct Answer
D:A local L route terminates traffic at the router for processing by the relevant IP service; it is not an instruction to forward that packet to another subnet host. The connected C network route handles adjacent subnet destinations.
Incorrect Answers
A:The /32 local host route is more specific and signifies the router’s address.
B:In IOS IPv4 RIB code L denotes local interface host address, not an OSPF LSA.
C:IOS normally installs both for an operational numbered IPv4 interface.
Question 295
A branch routing engineer must explain an outage. The configured next hop has no independent route, so the configured S destination never becomes a usable installed route. Which diagnosis follows from these observations?
- The configured route must be forwarding because it is present as text in running configuration.
- The absence of an OSPF hello timer necessarily hides every configured static route.
- The static destination has an unresolved next hop, preventing the intended route from becoming a usable forwarding entry.
- The route is necessarily present as an L /32 because its next hop is a host address.
Explanation
Correct Answer
C:An IOS static route typically requires its next-hop address to resolve via another usable route or a valid exit interface. Correct syntax alone does not guarantee active installation when recursive resolution fails.
Incorrect Answers
A:Configured state is not equivalent to an installed resolved RIB/FIB entry.
B:Static next-hop reachability is independent of OSPF timing unless OSPF supplies a relevant recursive route.
D:A remote next-hop host address is not the router’s local interface IP.
Question 296
An OSPFv2 transit link is up, but the interface was accidentally configured `passive-interface GigabitEthernet0/1`. No hellos leave that interface and no neighbor or expected O route forms. What repair addresses the verified fault?
- Raise the OSPF interface cost to make its routes less attractive.
- Remove the connected route to force an OSPF path to install.
- Remove passive mode from the transit interface while retaining OSPF advertisement on that network.
- Change the router ID after every interface flap.
Explanation
Correct Answer
C:A passive OSPF interface can advertise its connected prefix but does not send OSPF hellos or form neighbors. A router-to-router transit must not be passive when adjacency is required.
Incorrect Answers
A:Cost controls preference among eligible OSPF paths, but a cost change cannot establish adjacency while hellos are suppressed.
B:Deleting a connected route does not reenable OSPF hellos and can remove necessary transport reachability.
D:A stable router ID is useful, but changing it has no bearing on the explicitly passive transit interface stopping hellos.
Question 297
A packet enters a Cisco router from source 10.0.0.10 toward destination 198.51.100.18. The RIB contains usable routes 198.51.100.0/24 via R2 and 0.0.0.0/0 via R3; no policy-based routing is configured. Which forwarding decision is correct?
- Choose the route to the packet’s source subnet and ignore the destination 198.51.100.18.
- Always forward via the 0/0 default despite an installed more-specific destination match.
- Use the lower administrative distance of any unrelated source-prefix route to select the egress.
- The next hop is chosen from the installed route matching destination 198.51.100.18, unless an explicit feature such as policy-based routing changes the behavior.
Explanation
Correct Answer
D:Ordinary IP forwarding uses a destination lookup with longest matching prefix. A source address can influence policy routing only when such a policy is configured; no such feature is stated here.
Incorrect Answers
A:Source subnet is not the normal destination FIB lookup key.
B:A longest matching destination route takes precedence over default.
C:AD comparisons do not replace matching the packet’s destination network.
Question 298
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. The team should investigate which specific technical cause?
- 192.0.2.0/25 covers all of 192.0.2.0–255 because the first three octets match.
- 192.0.2.200 belongs to the 192.0.2.128/25 upper half, not 192.0.2.0/25; install or match the correct prefix.
- 192.0.2.200 belongs to 192.0.2.0/26 because /26 is less specific than /25.
- Any 192.0.2.x address matches a local L /32 if the router owns only 192.0.2.1.
Explanation
Correct Answer
B:A /25 subnet mask is 255.255.255.128, so 192.0.2.0/25 spans .0–.127 and 192.0.2.128/25 spans .128–.255. A route for the first half cannot match .200.
Incorrect Answers
A:That is a /24 interpretation; the /25 high bit divides the fourth octet.
C:The first /26 ends at .63 and is even narrower than the first /25.
D:An L /32 matches exactly the local host IP, not arbitrary addresses in the /24.
Question 299
R1 has an installed static route `S 203.0.113.0/24 via 192.0.2.2`. Its Gi0/1 interface is up and has a connected 192.0.2.0/30, so 192.0.2.2 is on-link. However, `show ip arp 192.0.2.2` shows an incomplete entry, and traffic using the static route fails. Which finding best identifies the immediate forwarding problem?
- A missing IP route to 192.0.2.2 prevents recursive resolution, despite the connected /30.
- The static route is installed, but the Layer 2 ARP adjacency for its on-link next hop remains unresolved.
- OSPF always overrides static routes when its advertised metric is lower.
- The 203.0.113.0/24 route only matches the lower half of that /24 prefix.
Explanation
Correct Answer
B:This is the key distinction: the IPv4 route is present and its next hop is on a connected Ethernet subnet, but no usable destination MAC for 192.0.2.2 has been learned. Check the peer interface, VLAN, cabling and ARP filtering before changing route preference.
Incorrect Answers
A:The connected 192.0.2.0/30 already provides RIB reachability to 192.0.2.2, so missing recursive route information is not the observed issue. The incomplete ARP entry is a separate Layer 2 resolution failure.
C:The route is explicitly installed as static; its own destination prefix and next-hop resolution are not determined by comparing OSPF metric with static cost. Moreover, the missing MAC is evidence of failed adjacency, not a control-plane route-source contest.
D:A /24 covers all addresses from 203.0.113.0 through 203.0.113.255; it is not limited to half the range. The failure is at the Ethernet next-hop mapping for 192.0.2.2, not at prefix length selection.
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.
