CCNA Network Infrastructure and Connectivity Practice Test 22 — 15 Questions

Question 1

You are connected to R1. Configure the G0/0 interface to match the speed (100 Mbps) and duplex (full) of the connected switch port, then diagnose and fix an auto-negotiation failure that has caused excessive CRC errors. Finally, select and replace the SFP module on G0/0 with one that supports a 5 km fiber link, using the correct cable type.

Accepted Answer

Set speed 100, duplex full; replace SFP with 1000BASE-LX; use single-mode fiber (SMF).. The interface is up but line protocol is down, indicating a layer 1 issue. The switch port is manually set to 100 Mbps/full duplex, but R1 is using auto-negotiation, causing a mismatch. First, set the speed to 100 and duplex to full on G0/0. The CRC errors may appear later if cabling is faulty; for a 5 km fiber link, you need a 1000BASE-LX SFP (single-mode) and single-mode fiber (SMF). Verify the SFP is recognized and the link comes up.

Answer

Set speed 100, duplex half; replace SFP with 1000BASE-SX; use multimode fiber (MMF).

Answer

Set speed 1000, duplex full; replace SFP with 1000BASE-LX; use single-mode fiber (SMF).

Answer

Set no speed, no duplex (auto); replace SFP with 1000BASE-LX; use single-mode fiber (SMF).

Question 2

You are connected to R1 via the console. R1 and R2 are directly connected via their GigabitEthernet0/0 interfaces. The link between them is down. Your task is to diagnose and fix the issue: R1's interface is configured for 100 Mbps full-duplex, but R2 is using auto-negotiation. Additionally, the link requires a Gigabit Ethernet connection over a distance of 5 km. Configure R1's interface to match R2's settings (auto-negotiation) and then select and install the correct SFP module to support the 5 km distance requirement.

Accepted Answer

Configure R1 with 'no speed', 'no duplex', and 'negotiation auto' on GigabitEthernet0/0, then replace the SFP module with a 1000BASE-LX SFP.. The link is down because R1 is forcing speed 100 and full-duplex while R2 is using auto-negotiation. When one side is hard-coded and the other is set to auto, auto-negotiation fails and the link does not come up. The fix is to enable auto-negotiation on R1 by removing the manual speed and duplex settings with the 'no speed' and 'no duplex' commands, and then using 'negotiation auto'. For the 5 km distance, a standard 1000BASE-SX SFP (550 m) is insufficient; a 1000BASE-LX SFP (up to 10 km) is required. The candidate must also replace the SFP module with a compatible LX SFP.

Answer

Configure R1 with 'speed 1000' and 'duplex full' on GigabitEthernet0/0, then replace the SFP module with a 1000BASE-SX SFP.

Answer

Configure R1 with 'no speed', 'no duplex', and 'negotiation auto' on GigabitEthernet0/0, then replace the SFP module with a 1000BASE-SX SFP.

Answer

Configure R1 with 'speed 100' and 'duplex full' on GigabitEthernet0/0, then replace the SFP module with a 1000BASE-LX SFP.

Question 3

You are connected to R1 via the console. R1 and R2 are connected via a fiber link using SFPs. The link is not coming up. Configure the correct SFP type on R1's interface GigabitEthernet0/0 to support the required 2 km distance, and fix any auto-negotiation or speed/duplex misconfiguration so that the link becomes operational.

Accepted Answer

Replace SFP with 1000BASE-LX, configure 'no negotiation auto' on GigabitEthernet0/0, and remove 'speed 1000' and 'duplex full'.. The current SFP is 1000BASE-SX (850 nm), rated for only 550 m, which is insufficient for a 2 km link. It must be replaced with a 1000BASE-LX SFP that supports up to 10 km. The interface currently has 'speed 1000', 'duplex full', and 'negotiation auto'. On fiber SFPs, auto-negotiation is not supported and the speed and duplex are fixed at 1000 Mbps full duplex; therefore, 'no negotiation auto' is required, and any manually configured speed/duplex that violates the SFP's capabilities will prevent the link from coming up. Option A correctly uses 1000BASE-LX, disables auto-negotiation, and removes the redundant speed/duplex commands (the defaults are sufficient). Option D incorrectly sets 'speed 100', which is incompatible with the 1000BASE-LX SFP, causing the link to fail. Option B uses the wrong SFP type (1000BASE-SX). Option C uses the correct SFP but leaves 'negotiation auto', which is unsupported on fiber SFPs and will keep the link down.

Answer

Replace SFP with 1000BASE-SX, configure 'negotiation auto' on GigabitEthernet0/0, and keep 'speed 1000' and 'duplex full'.

Answer

Replace SFP with 1000BASE-LX, configure 'negotiation auto' on GigabitEthernet0/0, and keep 'speed 1000' and 'duplex full'.

Answer

Replace SFP with 1000BASE-LX, configure 'no negotiation auto' on GigabitEthernet0/0, and configure 'speed 100' and 'duplex full'.

Question 4

You are troubleshooting a link between R1 (G0/0) and R2 (G0/0). The link is up but experiencing packet loss. You suspect an interface speed/duplex mismatch or SFP issue. Configure R1's interface to match the correct speed and duplex, and replace the SFP module if necessary to support a required distance of 40 km over single-mode fiber.

Accepted Answer

Remove manual speed/duplex settings, enable auto-negotiation, and replace the SFP with a long-reach module (e.g., 1000BASE-ZX) that supports 40 km over single-mode fiber.. The link is experiencing packet loss, likely due to a speed/duplex mismatch between the manually configured interface and the peer (which may use auto-negotiation) and/or an SFP module that cannot support the required 40 km distance over single-mode fiber. To resolve both potential issues, remove any manual speed and duplex settings to restore default auto-negotiation (using 'no speed' and 'no duplex'), and replace the SFP with a module rated for 40 km or more on SMF, such as a 1000BASE-ZX (or 1000BASE-EX) transceiver. Standard 1000BASE-LX/LH only reaches up to 10 km on SMF, so it is insufficient for this scenario.

Answer

Change the duplex to full and speed to 1000 Mbps manually, and keep the existing SFP.

Answer

Keep the manual speed/duplex settings but replace the SFP with a 1000BASE-SX module.

Answer

Enable auto-negotiation on both ends but keep the existing SFP.

Question 5

You are connected to R1 via console. R1 is directly connected to R2 over a 1000BASE-T link that is failing to come up. Configure interface GigabitEthernet0/0 on R1 with the correct speed and duplex settings to match R2's configuration, and then verify the link is operational. Additionally, determine the appropriate SFP type for a new 40 km fiber link between R1 and R2.

Accepted Answer

Configure interface GigabitEthernet0/0 with 'speed 1000' and 'duplex full'. For the new fiber link, use a 1000BASE-ZX SFP.. The link is down because R1 is set to auto-negotiate speed and duplex while R2 is hardcoded to 1000 Mbps full duplex. This mismatch causes the link to fail. To fix, configure R1's GigabitEthernet0/0 with 'speed 1000' and 'duplex full'. For the new 40 km fiber link, a 1000BASE-ZX SFP is required as it supports distances up to 70 km. (1000BASE-LX supports only up to 10 km and is insufficient for 40 km.) Verify with 'show interfaces GigabitEthernet0/0' to see the link state change to up/up.

Answer

Configure interface GigabitEthernet0/0 with 'speed auto' and 'duplex auto'. For the new fiber link, use a 1000BASE-SX SFP.

Answer

Configure interface GigabitEthernet0/0 with 'speed 1000' and 'duplex half'. For the new fiber link, use a 1000BASE-LX SFP.

Answer

Configure interface GigabitEthernet0/0 with 'speed 100' and 'duplex full'. For the new fiber link, use a 1000BASE-EX SFP.

Question 6

You are connected to R1. The link between R1's GigabitEthernet0/0 and R2's GigabitEthernet0/0 should operate at 1 Gbps full duplex, but the interface is showing errors and only negotiating at 100 Mbps half duplex. Diagnose and fix the fault, then verify the link is stable at the correct speed and duplex.

Accepted Answer

Remove the manual speed and duplex settings on R1's GigabitEthernet0/0 with 'no speed' and 'no duplex' to allow auto-negotiation.. The interface was manually configured with 'duplex half' and 'speed 100', which forced the link to 100 Mbps half duplex, causing CRC errors due to duplex mismatch. The correct fix is to remove these manual settings and allow auto-negotiation, or explicitly set both sides to 'speed 1000' and 'duplex full'. Since the remote side (R2) is set to auto (default), the simplest correction is to use 'no duplex' and 'no speed' on R1 to re-enable auto-negotiation. After the commands are applied, the interface should show 'Full-duplex, 1000Mb/s' and CRC errors should stop incrementing.

Answer

Change the duplex setting to 'full' and speed to '1000' on R1's GigabitEthernet0/0.

Answer

Replace the cable between R1 and R2 with a crossover cable.

Answer

Configure R2's GigabitEthernet0/0 with 'speed 100' and 'duplex half' to match R1's settings.

Question 7

You are connected to R1 via console. The link between R1 and R2 is experiencing packet loss and CRC errors. Configure interface speed and duplex on R1's GigabitEthernet0/0 to match R2's settings, then replace the SFP module with one that supports the required 2 km distance. Finally, verify the interface is operational without errors.

Accepted Answer

Configure speed 1000, duplex full, and no negotiation auto on Gi0/0, then replace the SFP-GE-SX with SFP-GE-L.. The CRC errors indicate a duplex mismatch or faulty medium. R1 is set to auto-negotiation while R2 is hardcoded to 1000/full, causing mismatch. First, set speed and duplex on R1 to match R2: 'speed 1000' and 'duplex full'. Also disable auto-negotiation with 'no negotiation auto'. The existing SFP-GE-SX only supports 550m, but the link requires 2 km; replace it with a 1000BASE-LX/LH SFP (SFP-GE-L) which supports up to 10 km. After changes, verify with 'show interfaces Gi0/0' to confirm no CRC errors and correct speed/duplex.

Answer

Configure speed 1000 and duplex full on Gi0/0, then replace the SFP-GE-SX with SFP-GE-SX-MM.

Answer

Configure speed 100 and duplex full on Gi0/0, then replace the SFP-GE-SX with SFP-GE-L.

Answer

Configure no negotiation auto on Gi0/0, then replace the SFP-GE-SX with SFP-GE-L.

Question 8

You are connected to the console of R1. The network administrator reports that hosts in VLAN 10 cannot reach the server at 192.168.1.100. R1 is the default gateway for VLAN 10 via subinterface G0/0.10. The link between R1 and the switch SW1 appears to be up, but pings fail. Your task is to identify and resolve the issue.

Accepted Answer

Check the duplex and speed settings on the physical interface G0/0 of R1 and the corresponding switchport on SW1; they may be mismatched.. The link between R1 and SW1 had mismatched duplex/speed settings because auto-negotiation failed, causing excessive CRC errors and packet loss. Manually setting both sides to 100/full resolves the issue.

Answer

Check the interface status on R1's G0/0.10 subinterface; it may be administratively down.

Answer

Verify that the VLAN 10 SVI on SW1 has an IP address in the correct subnet.

Answer

Ensure that the native VLAN on the trunk between R1 and SW1 is VLAN 1.

Question 9

You are connected to SW1 via the console. The network uses VLANs 10 (Sales) and 20 (Engineering). A new switch SW2 is connected to SW1 via G0/1. You need to enable CDP to discover neighbor devices and verify that SW1 sees SW2. Currently, CDP is disabled globally.

Accepted Answer

Enable CDP globally with 'cdp run' and verify with 'show cdp neighbors'.. CDP is disabled globally with 'no cdp run'. Re-enabling with 'cdp run' allows SW1 to discover directly connected Cisco devices, including SW2. Option B is incorrect because interface-level 'cdp enable' requires CDP to already be enabled globally; since CDP is globally disabled, this command has no effect. Option C is incorrect because 'show cdp interface' displays CDP parameters per interface, not the neighbor table; you need 'show cdp neighbors' to see discovered devices. Option D is incorrect because 'cdp enable' is not a valid global command; the correct global command is 'cdp run'.

Answer

Enable CDP on interface G0/1 with 'cdp enable' and verify with 'show cdp neighbors'.

Answer

Enable CDP globally with 'cdp run' and verify with 'show cdp interface'.

Answer

Enable CDP globally with 'cdp enable' and verify with 'show cdp neighbors'.

Question 10

You are connected to R1 via the console. R1 is a new router that needs to be configured with a hostname, an encrypted privileged password 'cisco123', and a banner message 'Unauthorized access prohibited'. Additionally, SSH must be enabled for remote management using a domain name 'example.com' and a key size of 1024. The management interface is G0/0 with IP 192.168.1.1/24.

Accepted Answer

hostname R1
enable secret cisco123
banner motd #Unauthorized access prohibited#
ip domain-name example.com
crypto key generate rsa modulus 1024
line vty 0 4
transport input ssh
login local
interface g0/0
ip address 192.168.1.1 255.255.255.0
no shutdown. Configuring hostname, enable secret, and banner sets basic identity and security. Generating RSA keys with a domain name enables SSH; then VTY lines are restricted to SSH only.

Answer

hostname R1
enable password cisco123
banner motd #Unauthorized access prohibited#
ip domain-name example.com
crypto key generate rsa modulus 1024
line vty 0 4
transport input ssh
password cisco123
login
interface g0/0
ip address 192.168.1.1 255.255.255.0
no shutdown

Answer

hostname R1
enable secret cisco123
banner motd #Unauthorized access prohibited#
ip domain-name example.com
crypto key generate rsa modulus 1024
line vty 0 4
transport input ssh
password cisco123
login local
interface g0/0
ip address 192.168.1.1 255.255.255.0
no shutdown

Answer

hostname R1
enable secret cisco123
banner motd #Unauthorized access prohibited#
ip domain-name example.com
crypto key generate rsa modulus 1024
line vty 0 4
transport input ssh
login local
username admin secret cisco123
interface g0/0
ip address 192.168.1.1 255.255.255.0
no shutdown

Question 11

You are connected to the console of R1. The network uses IPv6 and you need to configure an IPv6 address on interface G0/0 using the EUI-64 format. The subnet is 2001:db8:acad:1::/64. The interface MAC address is 0011.2233.4455. After configuration, verify that the full IPv6 address is correct.

Accepted Answer

ipv6 address 2001:db8:acad:1:0211:22ff:fe33:4455/64. The EUI-64 method inserts FFFE in the middle of the MAC and flips the U/L bit. With the given MAC, the resulting interface ID is 0211:22FF:FE33:4455, forming the full IPv6 address.

Answer

ipv6 address 2001:db8:acad:1:0011:22ff:fe33:4455/64

Answer

ipv6 address 2001:db8:acad:1:0011:2233:4455/64

Answer

ipv6 address 2001:db8:acad:1:0211:2233:4455/64

Question 12

You are connected to the console of R1. The network administrator reports that hosts on VLAN 10 cannot ping the default gateway (192.168.10.1). R1's GigabitEthernet0/1 is connected to a switch with trunk port allowing VLAN 10 and 20. The interface configuration on R1 appears correct, but the VLAN 10 interface is not operational.

Accepted Answer

The physical interface GigabitEthernet0/1 was administratively down.. The GigabitEthernet0/1 interface was administratively down (missing 'no shutdown' in the initial config). Although the subinterface had 'no shutdown', the physical interface must also be up. Bringing up the physical interface resolved the issue.

Answer

The VLAN 10 subinterface was configured with the wrong encapsulation dot1q VLAN ID.

Answer

The switch port connected to R1 was not configured as a trunk.

Answer

The VLAN 10 subinterface was missing the 'no shutdown' command.

Question 13

You are connected to the console of R1. The network uses IPv6 with EUI-64. R1's GigabitEthernet0/0 has MAC address 0011.2233.4455. You need to configure an IPv6 address on this interface using the prefix 2001:db8:1:1::/64 with EUI-64, and ensure the interface is operational.

Accepted Answer

ipv6 address 2001:db8:1:1::/64 eui-64. Option B uses the correct syntax 'ipv6 address 2001:db8:1:1::/64 eui-64', which configures the prefix and derives the interface ID automatically from the MAC address via EUI-64. Option A is invalid because specifying the full 128-bit address with the eui-64 keyword is not allowed; the eui-64 keyword requires only a prefix. Option C omits the eui-64 keyword, so it configures a static address without using EUI-64, which would not match the requirement to use EUI-64. Option D appends the MAC address after the eui-64 keyword, which is invalid syntax; the eui-64 keyword does not accept an explicit MAC address.

Answer

ipv6 address 2001:db8:1:1:0011:22ff:fe33:4455/64 eui-64

Answer

ipv6 address 2001:db8:1:1:0211:22ff:fe33:4455/64

Answer

ipv6 address 2001:db8:1:1::/64 eui-64 0011.2233.4455

Question 14

You are connected to the console of R1. The network has a point-to-point serial link between R1 and R2. The link is down and the line protocol is down. The cable is a DCE/DTE crossover, and R1 is the DCE. The initial configuration shows the interface with an IP address but no clock rate set.

Accepted Answer

Configure the clock rate on R1's serial interface.. On a serial DCE cable, the DCE end must configure a clock rate to provide timing. Without it, the line protocol stays down. Setting 'clock rate 128000' on R1 resolved the issue.

Answer

Configure the clock rate on R2's serial interface.

Answer

Replace the serial cable with a straight-through cable.

Answer

Set the encapsulation on both ends to PPP.

Question 15

You are connected to the console of SW1. The network administrator reports that SW1 cannot discover neighbouring devices using CDP. SW1 is connected to R1 via GigabitEthernet0/1. CDP is globally enabled, but still no neighbours are shown.

Accepted Answer

Enable CDP on interface GigabitEthernet0/1 with the command 'cdp enable'.. CDP was globally enabled but the interface GigabitEthernet0/1 had CDP disabled by default (or was explicitly disabled). Enabling CDP on the interface allowed neighbour discovery.

Answer

Enable CDP globally with the command 'cdp run'.

Answer

Use the command 'lldp run' to enable LLDP as an alternative.

Answer

Check the physical cable and interface status on GigabitEthernet0/1.

CCNA Network Infrastructure and Connectivity Practice Test 22 — 15 Questions

Exhibit

CCNA Network Infrastructure and Connectivity Practice Test 22 — 15 Questions

Exhibit