CCNA Network Infrastructure and Connectivity Practice Test 6 — 15 Questions

Question 1

Drag and drop the following troubleshooting steps into the correct order to diagnose client connectivity using the OSI bottom-up method.

Accepted Answer

Check physical cabling and link lights. The OSI bottom-up troubleshooting method starts at Layer 1 and proceeds upward. The correct order is: (A) Check physical cabling and link lights (Layer 1), (B) Verify VLAN assignment and switchport configuration (Layer 2), (C) Test IP configuration and default gateway (Layer 3), and (D) Check DNS resolution and application settings (Layer 7). Each step builds on the previous layer to isolate connectivity issues.

Question 2

Which TWO tools or commands are commonly used to troubleshoot wireless client connectivity issues on a Cisco WLAN?

Accepted Answer

ping. The ping command (A) tests basic IP-layer connectivity from the wireless client to a target host, revealing whether the client has a valid IP and can reach the default gateway or servers. The show wireless client summary command (E) is a standard WLC diagnostic command that displays associated clients’ MAC addresses, IP addresses, VLAN assignments, and authentication states, enabling quick identification of connectivity issues at the wireless link layer. Option B, ipconfig /release, only releases the client’s DHCP lease and does not diagnose ongoing connectivity. Option C, traceroute, traces the path to a destination, which is not a primary wireless client troubleshooting tool; it is more suited for routing analysis. Option D, show running-config, displays the device’s static configuration, not live client connectivity. Option F, debug dhcp detail, is a high-impact debug that is too granular for general wireless troubleshooting and can disrupt service.

Answer

ipconfig /release

Answer

traceroute

Answer

show running-config

Answer

debug dhcp detail

Question 3

You are connected to R1. The connection between R1 and R2 is experiencing intermittent failures. You issue the show interfaces GigabitEthernet0/0 command on R1 and the output shows: GigabitEthernet0/0 is up, line protocol is up (looped). Troubleshoot the interface G0/0 on R1 to identify and resolve the issue so that the link becomes stable and operational.

Accepted Answer

Enter interface configuration mode for G0/0 and issue the 'no loopback' command.. The interface is in loopback test mode, as indicated by the '(looped)' status on the line protocol. This loopback test prevents normal data forwarding. To resolve it, remove the loopback configuration using 'no loopback' on interface G0/0. Afterwards, verify the interface status returns to 'up, line protocol is up' without the loop indication.

Answer

Enter interface configuration mode for G0/0 and issue the 'no shutdown' command.

Answer

Enter interface configuration mode for G0/0 and issue the 'speed 100' command to force 100 Mbps.

Answer

Enter interface configuration mode for G0/0 and issue the 'no keepalive' command.

Question 4

You are connected to R1 via the console. The link between R1 and R2 is experiencing intermittent connectivity. A 'show interfaces GigabitEthernet0/0' output shows the interface is up/up, line protocol up, Full-duplex, 1000Mb/s, but there are 1234 input errors, including 567 CRC errors. Identify the root cause of the issue, and apply the necessary configuration fix to restore full connectivity.

Accepted Answer

Configure the interface with 'duplex auto' and 'speed auto'.. The output indicates high CRC errors on a GigabitEthernet interface operating at 1000 Mb/s and full-duplex. Since 1000BASE-T does not support half-duplex, a duplex mismatch is not possible. The CRC errors likely result from a speed or duplex negotiation mismatch where one side uses forced settings (e.g., speed 1000 duplex full) and the other uses auto-negotiation, causing physical layer instability. Setting both sides to auto-negotiation ('duplex auto' and 'speed auto') allows them to properly agree on the highest common speed and duplex, resolving the errors. Option A forces full and 1000, which may not match R2 if it is set to auto, so it is not a reliable fix. Option B uses 'duplex half', which is invalid on Gigabit links and would break connectivity. Option C's 'no shutdown' is irrelevant because the interface is already administratively up.

Answer

Configure the interface with 'duplex full' and 'speed 1000'.

Answer

Configure the interface with 'duplex half' and 'speed 100'.

Answer

Configure the interface with 'no shutdown' to re-enable the interface.

Question 5

You are troubleshooting connectivity between R1 and R2. The link is up but users report intermittent packet loss. Examine the provided show interface output on R1, identify the root cause, and apply the necessary fix to restore normal operation.

R1# show interface GigabitEthernet0/0
GigabitEthernet0/0 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet, address is 0011.2233.4455
  MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, media type is RJ45
  input flow-control is off, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:01, output 00:00:01, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 1000 bits/sec, 1 packets/sec
  5 minute output rate 1000 bits/sec, 1 packets/sec
     2453 packets input, 213456 bytes, 0 no buffer
     Received 500 broadcasts (0 multicasts)
     0 runts, 0 giants, 0 throttles
     312 input errors, 312 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     3211 packets output, 345678 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out

Accepted Answer

Replace the faulty cable between R1 and R2.. The output shows the interface is operating at Full-duplex, 1000Mb/s, but is experiencing a high number of input errors and CRC errors. On Gigabit Ethernet, a duplex mismatch is not possible because 1000BASE-T operates in full-duplex mode only. The CRC and input errors point to physical layer problems, such as a faulty cable or connector, causing intermittent packet loss. Replacing the cable between R1 and R2 is the appropriate fix.

Answer

Configure 'duplex auto' and 'speed auto' on interface G0/0 of R1.

Answer

Increase the MTU size on interface G0/0 of R1.

Answer

Disable CDP on interface G0/0 of R1.

Question 6

You are troubleshooting connectivity between R1 and R2. R1's Gi0/0 interface is connected to R2's Gi0/0. R1 can ping its own IP but cannot ping R2's IP. Examine the provided 'show interfaces' output on R1 and identify the root cause. Then, apply the necessary configuration command(s) on R1 to resolve the issue.

R1# show interfaces GigabitEthernet0/0
GigabitEthernet0/0 is up, line protocol is down
  Internet address is 192.168.1.1/24
  Half-duplex, 10Mb/s, media type is RJ45

Accepted Answer

interface GigabitEthernet0/0
 duplex full
 speed 1000. A line protocol down with interface up typically indicates a Layer 2 problem such as a speed/duplex mismatch. The proper resolution is to configure both ends with matching speed and duplex. In this scenario, the remote interface is assumed to operate at 1000 Mbps full-duplex, so R1 must be set to speed 1000 and duplex full. Option A accomplishes this.

Answer

interface GigabitEthernet0/0
 no shutdown

Answer

interface GigabitEthernet0/0
 ip address 192.168.1.1 255.255.255.0

Answer

interface GigabitEthernet0/0
 no keepalive

Question 7

You are connected to R1. The network administrator reports that the link between R1 and R2 is flapping and performance is poor. Examine the provided show interface output on R1, identify the root cause of the issue, and apply the necessary configuration fix to resolve the problem permanently.

```
R1# show interfaces FastEthernet 0/1
FastEthernet0/1 is up, line protocol is up (connected)
  Hardware is Fast Ethernet, address is 0000.0000.0001 (bia 0000.0000.0001)
  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Half-duplex, 100Mb/s, media type is 10/100BaseTX
  input flow-control is off, output flow-control is off
  Last input 00:00:00, output 00:00:00, output hang never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     1025 packets input, 70000 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     1421 input errors, 1200 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     2000 packets output, 150000 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
```

Accepted Answer

Configure the interface with the 'duplex full' command.. Assuming the interface is a FastEthernet (or Ethernet) interface: The show interface output indicates half-duplex operation with high CRC errors and input errors, classic symptoms of a duplex mismatch with R2 set to full-duplex. Configuring 'duplex full' forces R1 to match R2 and resolves the mismatch. Option B only sets speed, leaving duplex mismatched. Option C is irrelevant because the interface is administratively up. Option D (duplex auto) would autonegotiate; but if R2 is forced full, autonegotiation fails and defaults to half-duplex, recreating the mismatch. Therefore, 'duplex full' is the correct fix.

Answer

Configure the interface with the 'speed 100' command.

Answer

Configure the interface with the 'no shutdown' command.

Answer

Configure the interface with the 'duplex auto' command.

Question 8

You are connected to R1 via console. The network administrator has partially configured IPv4 and IPv6 addressing on R1 and R2, but R1 cannot reach R2's GigabitEthernet0/1 interface at 203.0.113.2/24. Additionally, R1's IPv6 address on GigabitEthernet0/0 must be configured using EUI-64 based on the link-local address FE80::/10. Examine the current configuration, identify and fix the IPv4 issue, then complete the IPv6 configuration so that R1 can ping both R2's IPv4 and IPv6 addresses.

Accepted Answer

Enable IPv6 unicast-routing globally, then on GigabitEthernet0/0 configure ipv6 address autoconfig default.. The IPv4 issue is that R1 cannot reach R2's G0/1 because the interfaces are on the same subnet (203.0.113.0/24), so no route is needed; the problem may be that IPv6 is not enabled or configured. Option D enables IPv6 unicast-routing globally, which is required for IPv6 to function, and configures IPv6 autoconfig on G0/0, which uses EUI-64 by default to generate a global unicast address. The stem's mention of "based on the link-local address FE80::/10" is likely a distractor; autoconfig will derive the interface ID from the MAC. Options A, B, and C either add unnecessary routes, change the subnet mask incorrectly, or use a manual address instead of EUI-64.

Answer

Configure a default route on R1: ip route 0.0.0.0 0.0.0.0 192.0.2.2. Then on GigabitEthernet0/0, configure ipv6 address 2001:DB8::/64 eui-64.

Answer

Change the subnet mask on R1's GigabitEthernet0/1 to /30, then configure ipv6 address FE80::/10 eui-64 on GigabitEthernet0/0.

Answer

Add a static route on R1: ip route 203.0.113.0 255.255.255.0 192.0.2.2, then configure ipv6 address 2001:DB8::1/64 on GigabitEthernet0/0.

Question 9

You are connected to R1. Configure IPv4 and IPv6 addressing on R1's GigabitEthernet0/0 and GigabitEthernet0/1 interfaces so that R1 can reach R2 and the internal host on VLAN 10. R1 G0/0 connects to R2 (198.51.100.0/24), and R1 G0/1 connects to a switch with VLAN 10 (192.168.1.0/24). The current configuration has a wrong subnet mask on G0/0, missing IPv6 addresses, and a duplicate IP on G0/1. Fix all issues and verify connectivity.

Accepted Answer

On G0/0, change subnet mask to 255.255.255.0, add IPv6 address 2001:db8:1::1/64 and enable ipv6 enable; on G0/1, change IP to 192.168.1.254/24 and add IPv6 address 2001:db8:2::1/64.. The GigabitEthernet0/0 interface had a wrong subnet mask (255.255.255.252 instead of 255.255.255.0), causing R1 to think R2 (198.51.100.2) was on a different subnet, so pings failed. Additionally, IPv6 was not configured at all; we added a static global unicast address (2001:db8:1::1/64) and used the 'ipv6 enable' command on G0/0 to enable IPv6 and automatically generate a link-local address. On G0/1, the IP address 192.168.1.1 was already in use by another device (seen in ARP cache with age 0), so we changed it to 192.168.1.254 (the usual default gateway for VLAN 10). Finally, we verified with show commands and pings.

Answer

On G0/0, change subnet mask to 255.255.255.252, add IPv6 address 2001:db8:1::1/64; on G0/1, keep IP 192.168.1.1/24 and add IPv6 address 2001:db8:2::1/64.

Answer

On G0/0, change subnet mask to 255.255.255.0, add IPv6 address 2001:db8:1::1/64; on G0/1, change IP to 192.168.1.254/24 but do not configure IPv6.

Answer

On G0/0, keep subnet mask 255.255.255.252, add IPv6 address 2001:db8:1::1/64 and enable ipv6 enable; on G0/1, change IP to 192.168.1.254/24 and add IPv6 address 2001:db8:2::1/64.

Question 10

You are connected to R1. Configure IPv4 and IPv6 addressing on interfaces G0/0 and G0/1 so that R1 can reach R2's loopback0 (198.51.100.1/32) and R2 can reach R1's loopback0 (203.0.113.1/32). The current configuration has a wrong subnet mask on R1 G0/0 and a missing default gateway on R2, causing reachability failures. Additionally, configure IPv6 using EUI-64 on R1 G0/1 and static IPv6 on R2 G0/1 to enable IPv6 ping between the two routers. All devices are routers.

Accepted Answer

On R1 G0/0, change subnet mask to 255.255.255.252; on R2, add ip route 0.0.0.0 0.0.0.0 10.0.0.1; for IPv6, on R2 G0/1 change address to 2001:db8:1::2/64.. Option A correctly addresses all three issues: the wrong subnet mask on R1 G0/0 is fixed to /30 (255.255.255.252), which is the standard for point-to-point links and matches the 10.0.0.0/30 subnet; the missing default gateway on R2 is added as ip route 0.0.0.0 0.0.0.0 10.0.0.1, pointing to R1's G0/0 interface; and the IPv6 address on R2 G0/1 is corrected to 2001:db8:1::2/64 so that it is in the same subnet as R1's EUI-64 address (which will be in 2001:db8:1::/64). This enables both IPv4 and IPv6 reachability.

Answer

On R1 G0/0, change subnet mask to 255.255.255.0; on R2, add ip route 0.0.0.0 0.0.0.0 10.0.0.1; for IPv6, on R2 G0/1 change address to 2001:db8:1::2/64.

Answer

On R1 G0/0, change subnet mask to 255.255.255.252; on R2, add ip route 0.0.0.0 0.0.0.0 10.0.0.2; for IPv6, on R2 G0/1 change address to 2001:db8:2::2/64.

Answer

On R1 G0/0, change subnet mask to 255.255.255.252; on R2, add ip route 0.0.0.0 0.0.0.0 10.0.0.1; for IPv6, on R2 G0/1 change address to 2001:db8:1::2/64 and on R1 G0/1 use static IPv6 instead of EUI-64.

Question 11

You are connected to R1. The network has three routers: R1, R2, and R3. R1's G0/0 is connected to R2's G0/0, and R1's G0/1 is connected to R3's G0/1. The goal is to configure R1 so that it can ping both R2 (192.0.2.2/30) and R3 (2001:db8:1::2/64). Currently, R1 cannot ping R2 due to a wrong subnet mask on R1's G0/0, and R3 is using an IPv6 EUI-64 address but R1 has been given a static IPv6 address that conflicts. Fix both issues and verify connectivity.

Accepted Answer

On G0/0, change the subnet mask to 255.255.255.252; on G0/1, remove the static IPv6 address and configure an EUI-64 address.. The problem has two issues. First, R1's G0/0 has IP 192.0.2.1 but its subnet mask is incorrectly set to 255.255.255.0 (/24) instead of the required 255.255.255.252 (/30) that matches R2's /30. This mask mismatch causes R1 to misclassify the subnet, preventing successful ping to R2. The fix is to change the mask to 255.255.255.252. Second, R1's G0/1 is configured with a static IPv6 address that duplicates R3's EUI-64 generated address (e.g., 2001:db8:1::2). This duplicate address breaks communication. The correct solution is to remove the static IPv6 address and enable EUI-64 on G0/1, allowing R1 to derive a unique interface ID from its own MAC address.

Answer

On G0/0, change the IP address to 192.0.2.2/30; on G0/1, change the IPv6 address to 2001:db8:1::2/64.

Answer

On G0/0, change the subnet mask to 255.255.255.0; on G0/1, change the IPv6 address to 2001:db8:1::1/64 with EUI-64.

Answer

On G0/0, change the IP address to 192.0.2.2/30; on G0/1, remove the static IPv6 address and configure an EUI-64 address.

Question 12

You are troubleshooting a wireless client association failure on a Cisco WLC. A client reports it can see the SSID 'GuestNet' but fails to connect, while another client using the same SSID connects fine. You must check the WLC configuration, identify the cause, and fix it so that both clients can associate successfully.

Accepted Answer

Enable WPA3 Transition Mode and set PMF to Optional.. Update the explanation to avoid implying PMF itself forces WPA3. Instead, note that WPA3 requires PMF, so the failing legacy client must support WPA3. In transition mode, WPA2 clients can connect with WPA2 and PMF optional.

Answer

Change the WLAN security to WPA2-PSK only and disable PMF.

Answer

Disable PMF on the WLAN and keep WPA3 enabled.

Answer

Change the WLAN to use WPA2-PSK with PMF Required.

Question 13

You are connected to the WLC via its management IP 192.168.10.10. A new corporate SSID 'SecureCorp' must be configured for WPA3-Personal with PSK 'Cisco123' on the 5 GHz radio only. The SSID should be broadcast. The WLAN must be mapped to interface 'corp_vlan' (VLAN 100). After configuration, a wireless client reports it cannot see or connect to the SSID. Troubleshoot and resolve the client's association failure.

Accepted Answer

Enable SSID broadcast for the SecureCorp WLAN.. The client cannot see the SSID because SSID broadcast is disabled. Although the administrator intended to broadcast the SSID, the actual WLAN configuration has the broadcast setting turned off. To resolve this, enable SSID broadcast on the WLAN. The security and VLAN settings are correct. Enabling broadcast allows the client to discover the network without manual entry.

Answer

Change the security mode to WPA2-Personal with the same PSK.

Answer

Reconfigure the WLAN to use interface 'management' instead of 'corp_vlan'.

Answer

Disable the 5 GHz radio and enable the 2.4 GHz radio for the SecureCorp WLAN.

Question 14

You are connected to the console of switch SW1. A user on VLAN 10 reports they cannot reach the internet (203.0.113.1). The switch is configured as a Layer 3 switch with SVIs. Identify and correct the misconfiguration that prevents the user's default gateway from functioning. The user's PC has IP address 192.168.10.50/24 and uses 192.168.10.1 as its default gateway.

Accepted Answer

The SVI for VLAN 10 has 'no ip proxy-arp' configured, and there is no default route on the switch.. The switch's SVI for VLAN 10 has 'no ip proxy-arp' configured, which prevents it from responding to ARP requests for the default gateway IP address. Additionally, the switch lacks a default route to forward traffic to the internet. Option A correctly identifies both issues.

Answer

The SVI for VLAN 10 has the wrong IP address configured; it should be 192.168.10.254 instead of 192.168.10.1.

Answer

The switch has a default route pointing to 203.0.113.1, but the SVI for VLAN 10 is missing the 'ip helper-address' command.

Answer

The VLAN 10 interface is administratively down, and the switch needs to be reloaded to apply the configuration.

Question 15

You are troubleshooting a client connectivity issue on VLAN 10. The client PC1 is connected to switch SW1, which is connected to router R1 acting as the default gateway. PC1 can ping its own IP and the default gateway (10.1.10.1) but cannot reach the internet. Identify the fault and apply the necessary fix on R1.

Accepted Answer

Configure a default route on R1: ip route 0.0.0.0 0.0.0.0 10.1.10.254. PC1 can ping its own IP and the gateway (10.1.10.1) but not the internet (8.8.8.8). The router R1 has no default route to forward traffic to the internet. The fix is to configure a default route on R1 pointing to the next-hop IP address of the upstream router (e.g., 10.1.10.254). On Ethernet, you must specify a next-hop IP; specifying only an exit interface (like GigabitEthernet0/0) would cause the router to ARP for every destination and fail, so option D is incorrect.

Answer

Configure a static route on R1: ip route 8.8.8.8 255.255.255.255 10.1.10.254

Answer

Configure a default route on R1: ip route 0.0.0.0 0.0.0.0 10.1.10.1

Answer

Configure a default route on R1: ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/0