CCNA Practice Test 30 — 15 Questions

Question 1

A user reports they cannot access any network resources. A network administrator runs ipconfig on the user's Windows PC and sees an IPv4 address of 169.254.45.3/16. The administrator then pings the default gateway 10.0.0.1, which fails, and uses traceroute to 10.0.0.1, which shows only '1 * * * Request timed out.' What is the most likely cause of the problem?

Accepted Answer

The DHCP server is unreachable.. The 169.254.45.3/16 address is an Automatic Private IP Addressing (APIPA) address, assigned by Windows when a DHCP discovery fails. The failed ping and traceroute to the default gateway confirm that the PC has no IP connectivity to the network. Since the PC is on the same subnet as the DHCP server (10.0.0.0/24), the most likely cause is that the DHCP server is unreachable, preventing the PC from obtaining a valid IP address.

Answer

The PC's DNS server address is incorrect.

Answer

The switch port is in an administratively down state.

Answer

The Ethernet cable is unplugged from the PC.

Question 2

A trunk link between two switches is up, but voice phones connected through one access switch no longer receive the correct voice VLAN treatment. Data users still pass traffic. Which area should be checked first?

Accepted Answer

Whether the voice VLAN is being carried and handled correctly across the switching path.. The first area to check is the end-to-end handling of the voice VLAN across the switching path. In practical terms, the data VLAN can still work while the voice VLAN experiences a forwarding, configuration, or policy problem. Because the phones depend on the correct voice VLAN behavior, that VLAN path should be examined first rather than assuming the whole trunk is broken.

This is a selective-services troubleshooting question. One class of traffic can fail even when ordinary user data still works.

Answer

Whether OSPFv3 neighbors are fully adjacent on the phone switch ports.

Answer

Whether the wireless controller has the correct guest SSID.

Answer

Whether BGP uses a lower metric than the static route.

Question 3

Drag and drop the following steps into the correct order to configure inter-VLAN routing using a router-on-a-stick topology.

Accepted Answer

On the switch, create the necessary VLANs (e.g., VLAN 10 and VLAN 20) using the 'vlan' command.. Inter-VLAN routing via router-on-a-stick requires creating VLANs on the switch, placing access ports in those VLANs, configuring a trunk to the router with the correct native VLAN to avoid mismatch, enabling the physical router interface, and then defining subinterfaces per VLAN with 802.1Q encapsulation and IP addresses. This ensures traffic from different VLANs can be routed.

Question 4

A network engineer connects a new switch to an existing Rapid PVST+ campus network. The new switch is intended to serve as an additional access-layer switch, but after connecting its uplinks, the engineer discovers that the root bridge for VLAN 10 has changed to this new switch, and several access ports on other switches with PortFast and BPDU Guard enabled are now in err-disabled state. Some users report intermittent connectivity loss.

Accepted Answer

The new switch’s bridge priority is lower than the existing root bridge, and it was connected to a port with BPDU Guard enabled.. The new switch's bridge priority is lower (numerically smaller) than the existing root bridge, so it becomes the new root for VLAN 10. When it sends superior BPDUs out its uplinks, the neighboring switch's access ports with PortFast and BPDU Guard enabled receive these BPDUs, triggering err-disable state on those ports, causing connectivity loss.

Answer

The new switch was connected to a port configured as a trunk with a native VLAN mismatch.

Answer

The new switch has PortFast enabled on its uplinks.

Answer

The BPDU Guard feature was globally enabled on all ports, including trunk ports.

Question 5

Exhibit: Users complain of slow wireless performance in a dense office even though signal strength is strong. Multiple APs are using channels 1, 2, and 3 on 2.4 GHz. Which change is most appropriate?

Accepted Answer

Move to non-overlapping channels such as 1, 6, and 11. In 2.4 GHz, overlapping channels cause co-channel and adjacent-channel interference. The common non-overlapping choices are 1, 6, and 11. Moving away from overlapping channels usually improves performance in a dense deployment.

Answer

Reduce all AP transmit power to zero

Answer

Change every AP to the same channel for consistency

Answer

Disable WPA2 security

Question 6

Drag and drop the following steps into the correct order to configure a primary default static route and a floating default static route on a Cisco router.

Accepted Answer

Enter global configuration mode using the configure terminal command.. First, enter global configuration mode. Then configure the primary default route (no administrative distance specified, default 1). Next, configure the floating default route with a higher administrative distance (e.g., 5). Exit configuration mode, and finally verify the static routes in the routing table.

Question 7

Drag and drop the following steps into the correct order to configure Router R1 with OSPFv2 process 1 to form neighbor adjacencies only on GigabitEthernet0/1 while preventing OSPF hello packets on all other OSPF-enabled interfaces.

Accepted Answer

router ospf 1. First, enter OSPF router configuration mode. Then assign a Router ID (optional but good practice). Next, advertise the local subnet with a network statement to enable OSPF on interfaces. Then apply passive-interface default to suppress hellos on all OSPF interfaces. Finally, use no passive-interface to allow adjacency on the specific interface.

Question 8

Drag and drop the following steps into the correct order to configure a Cisco switch as a DHCP relay agent with DHCP snooping, where the DHCP server is located on a remote router.

Accepted Answer

Configure a DHCP pool with network, default gateway, and lease parameters on the router acting as the DHCP server.. First, the DHCP server must be properly configured on the router. Next, DHCP snooping is enabled globally on the switch to protect against rogue servers. Then, the specific client VLANs must be added to the snooping database. After that, the uplink interface to the DHCP server must be trusted to allow legitimate server responses. Finally, the ip helper-address command is placed on the client's SVI to forward DHCP broadcasts to the remote server.

Question 9

A switch port connected to an end host should forward traffic for one VLAN only and should not negotiate trunking. Which configuration approach best fits that requirement?

Accepted Answer

Configure the interface with `switchport mode access`. The best approach is to configure the interface as an access port. In plain language, this tells the switch that the interface is for a normal endpoint and should belong to one VLAN rather than carry multiple VLANs like a trunk. It also avoids reliance on dynamic trunk negotiation, which is usually unnecessary and potentially confusing for a user-facing connection.

This is a standard access-layer design principle. End hosts such as PCs and printers usually connect to access ports, not trunks. That is why the correct answer is the one centered on explicit access-port behavior.

Answer

Configure the interface with `switchport mode trunk`

Answer

Configure the interface with `switchport mode dynamic desirable`

Answer

Configure the interface with `no switchport`

Question 10

In AAA, which function determines what an authenticated user is allowed to do after login?

Accepted Answer

Authorization. Authentication verifies identity. Authorization determines permitted actions. Accounting records activity.

Answer

Authentication

Answer

Accounting

Answer

Encryption

Question 11

Which TWO actions does DHCP snooping perform by default on a Cisco switch?

Accepted Answer

It blocks DHCP server messages received on untrusted ports.. DHCP snooping is a Layer 2 security feature that filters DHCP messages and builds a binding table. By default, it blocks DHCP server messages on untrusted ports and dynamically creates a binding table mapping IP addresses to MAC addresses. It does not relay requests across VLANs or convert broadcasts to unicasts (those are relay agent functions).

Answer

It generates a Cisco Discovery Protocol packet for each DHCP request.

Answer

It relays DHCP requests across VLANs.

Answer

It converts DHCP broadcasts into unicasts.

Question 12

A user says the phone connected to a switch port works, but the attached PC does not get network access. What is the most likely switch-side issue?

Accepted Answer

The access VLAN for the PC is misconfigured. An IP phone can use a voice VLAN while the attached PC uses the access VLAN. If the access VLAN is missing or wrong, the phone may still work while the PC fails.

Answer

The voice VLAN should always match the access VLAN

Answer

PortFast blocks the PC from sending traffic

Answer

The phone requires the switch to be in trunk mode

Question 13

A switch port connected to an IP phone and a PC should separate voice traffic from data traffic while still using one physical edge connection. Which feature best supports that design?

Accepted Answer

Voice VLAN. A voice VLAN best supports that design. In practical terms, a Cisco-style voice VLAN allows the switch to carry voice traffic separately from user data even though the phone and PC share the same physical access connection. This is a common enterprise edge design because it lets the phone use one VLAN while the downstream PC uses another.

The key point is separation of traffic types over one edge port, not trunking between switches or link aggregation.

Answer

EtherChannel

Answer

Native VLAN

Answer

Loop guard

Question 14

Refer to the exhibit. A network engineer is investigating intermittent connectivity complaints on a gigabit uplink between two distribution switches. The engineer runs the show interfaces GigabitEthernet0/0 command on one of the switches. Based on the output, what is the most likely cause of the errors?

Accepted Answer

A damaged or faulty cable is causing excessive CRC errors.. The output shows a high number of CRC errors and runts, which typically indicate a Layer 1 physical-layer issue such as a damaged or faulty cable. CRC errors occur when frames fail the cyclic redundancy check due to signal degradation, noise, or physical damage to the cabling. On a gigabit uplink, this is the most likely cause of intermittent connectivity.

Answer

The interface is configured with an incorrect encapsulation type.

Answer

A duplex mismatch exists between the connected devices.

Answer

The interface is assigned to the wrong VLAN.

Question 15

Why is an extended ACL usually placed close to the source of the traffic being filtered?

Accepted Answer

To stop unwanted traffic earlier and conserve bandwidth. Extended ACLs can filter by source, destination, and protocol. Placing them near the source drops unwanted traffic before it crosses more of the network.

Answer

Because standard ACLs cannot be applied near the destination

Answer

To make NAT translation easier on inside interfaces

Answer

Because extended ACLs only work inbound on access interfaces