CCNA Practice Test 3 — 10 Questions

Question 1

A router has the following routes in its table: 172.16.0.0/16, 172.16.20.0/24, and 172.16.20.128/25. Which route is used for traffic to 172.16.20.200?

Accepted Answer

172.16.20.128/25. The /25 route is used because it is the most specific match. In plain language, the router looks for the narrowest route that still contains the destination address. Since 172.16.20.200 falls inside 172.16.20.128/25, that route wins over the broader /24 and /16 entries.

This is a direct longest-prefix-match question. It is meant to reinforce that specificity comes first in routing-table lookup. Broader routes remain useful, but they are not chosen when a more precise matching entry exists.

Answer

172.16.0.0/16

Answer

172.16.20.0/24

Answer

The default route

Question 2

Which TWO statements correctly describe the behavior of standard ACLs and their placement on interfaces?

Accepted Answer

Standard ACLs filter traffic based on source IP address only.. Standard ACLs filter traffic based solely on the source IP address, using numbers 1–99 or 1300–1999 in classic Cisco IOS. They do not consider destination IP, protocol, or port numbers. Because they lack granularity, placing them close to the destination (option D) prevents them from inadvertently blocking traffic that should be permitted, as they cannot distinguish between traffic destined for different services on the same destination host.

Answer

Standard ACLs should be placed as close to the source as possible.

Answer

Standard ACLs can filter traffic based on destination IP address.

Answer

Standard ACLs can filter traffic based on TCP or UDP port numbers.

Question 3

A switch trunk must carry VLANs 10, 20, and 30, but traffic for VLAN 20 is failing. The trunk allowed list on one side is `10,30`. What is the most likely cause?

Accepted Answer

VLAN 20 is missing from the allowed VLAN list on one side of the trunk.. The most likely cause is that VLAN 20 is not in the allowed VLAN list on one side of the trunk. Option B is incorrect because converting the trunk to an access port would block all other VLANs, not just fix VLAN 20. Option C is incorrect because there is no requirement that VLAN 20 must be the native VLAN; native VLAN is unrelated to allowed list filtration. Option D is incorrect because ISL vs 802.1Q does not affect per-VLAN filtering; the allowed list is a separate configuration independent of the encapsulation type.

Answer

The trunk must be converted to an access port for VLAN 20 to work.

Answer

VLAN 20 must always be the native VLAN.

Answer

The switches must both use ISL instead of 802.1Q.

Question 4

A router has both an OSPF route and a static route to the same destination. The static route has an administrative distance of 200. What is the expected behavior while the OSPF route remains available?

Accepted Answer

The static route remains a backup and is used only if the OSPF route is lost.. The static route with an administrative distance of 200 behaves as a floating backup. In plain language, the router keeps it in reserve and prefers the OSPF route while OSPF is healthy, because OSPF’s default administrative distance of 110 is lower and therefore more trusted. The static route does not disappear from the configuration, but it stays out of the active routing table unless the better route is lost.

This is a very common CCNA concept because it shows how routing preference works between different route sources. The higher-distance static route is not useless; it is intentionally configured so that it becomes active only during a failure. That design provides backup routing without interfering with the normal dynamic path. The correct answer is the one describing the static route as a standby or floating route rather than as the preferred path.

Answer

The static route overrides OSPF immediately because static routes always win.

Answer

Both routes must be installed simultaneously because they point to the same destination.

Answer

The router removes the OSPF route because the static route has a manually configured distance.

Question 5

A branch router is running single-area OSPF. An engineer wants an interface to advertise its connected network into OSPF but must prevent hello packets from being sent on that LAN segment. Which two actions achieve that goal?

Accepted Answer

Enable OSPF on the interface or matching network statement. In OSPF, a passive interface still advertises the connected network but does not send or process hello packets. So the interface must participate in OSPF, and then it must be made passive.

Answer

Set the interface network type to point-to-point

Answer

Apply distribute-list out on the interface

Question 6

Which THREE statements accurately describe the characteristics of NETCONF and RESTCONF for programmatic network configuration?

Accepted Answer

NETCONF uses XML-encoded RPCs over a secure transport such as SSH or TLS.. NETCONF uses XML-encoded Remote Procedure Calls (RPCs) over a secure transport such as SSH or TLS, making option B correct. RESTCONF supports both XML and JSON encoding and uses standard HTTP methods (GET, POST, PUT, PATCH, DELETE), so option C is correct. Both NETCONF and RESTCONF rely on YANG data models to define the structure of configuration and operational data, confirming option D. Option A is incorrect because NETCONF does not use HTTP methods; that is a characteristic of RESTCONF. Option E is wrong because RESTCONF does not use a separate commit operation; changes are applied immediately with each HTTP request, unlike NETCONF's candidate config and commit model.

Answer

NETCONF uses HTTP methods such as GET, POST, PUT, and DELETE to manipulate configuration data.

Answer

NETCONF uses a separate commit operation to apply changes, while RESTCONF uses a similar commit mechanism.

Question 7

A router has learned route 172.16.50.0/24 from OSPF with cost 20 and also has a static route to the same prefix with administrative distance 5. Which two statements are correct about route selection?

Accepted Answer

The static route is installed because it has the lower administrative distance. When the same prefix is learned from different routing sources, the router first compares administrative distance (AD). The static route with AD 5 wins over OSPF with AD 110, so option A is correct. Option C is correct because if the static route is removed, the OSPF route becomes the next best candidate and is installed. Option B is wrong since AD is compared before metrics like OSPF cost; a lower cost does not override a lower AD. Option D is wrong because only one route is installed per destination based on AD, not both.

Answer

The OSPF route is installed because cost 20 is lower than metric 0

Answer

Both routes are installed as equal-cost paths automatically

Question 8

A trunk link between two switches is operational, but one side shows a native VLAN mismatch warning. What is the main concern with that condition?

Accepted Answer

Untagged traffic may be associated with different VLANs on each end of the trunk. A native VLAN mismatch can cause untagged traffic to be interpreted as belonging to different VLANs on each end of the trunk. In plain language, the two switches disagree about where untagged frames belong. That can lead to confusing traffic behavior, reachability problems for certain flows, and operational warnings. It is not always a total outage, but it is a design inconsistency that should be corrected.

This matters because trunks carry multiple VLANs, and the native VLAN defines how untagged traffic is handled. If both ends do not agree, the logical treatment of those frames becomes inconsistent. The correct answer is the one that focuses on misclassification of untagged traffic, not on unrelated routing behavior.

Answer

All tagged VLAN traffic is automatically converted to routed traffic

Answer

The mismatch forces OSPF adjacency reset on all routers

Answer

The trunk can carry only one VLAN until the mismatch is cleared

Question 9

After a hub was connected to interface Gi0/10, the interface immediately entered errdisable state. The following syslog message was generated: '%PORT_SECURITY-2-PSECURE_VIOLATION: Security violation occurred on interface Gi0/10.' What is the strongest explanation for why Gi0/10 shut down?

Accepted Answer

Port security detected more MAC addresses than allowed on the interface.. The strongest explanation is a port-security violation caused by the switch seeing more secure MAC addresses than the interface allows. In practical terms, a hub or unmanaged device can cause multiple end hosts to appear behind one access port. If the interface is configured with a maximum of one secure MAC address, additional learned MACs trigger the violation action.

This is a realistic access-layer security scenario because the port does not fail randomly. It fails because the observed behavior violates the configured policy.

Answer

The interface received a superior BPDU and became the root port.

Answer

The hub forced the interface to become a routed port.

Answer

DHCP snooping always shuts a port when a hub is attached.

Question 10

A network administrator notices that a workstation connected to a Cisco switch port cannot communicate with other devices on the same VLAN. The switch port is up/up, but the workstation reports slow performance and intermittent connectivity. What is the most likely cause of this issue?

Accepted Answer

A duplex mismatch between the switch port and the workstation.. A duplex mismatch occurs when one end of the link is set to full-duplex and the other to half-duplex. The half-duplex end detects collisions and the full-duplex end does not, causing late collisions, CRC errors, and retransmissions. This results in slow performance and intermittent connectivity even though the port is operationally up.

Answer

Replace the faulty Ethernet cable between the switch and the workstation.

Answer

Assign the switch port to the correct VLAN.

Answer

Disable spanning-tree on the port to prevent frequent topology changes.