100-150 Practice Test 14 — 15 Questions

Question 1

A network administrator is replacing older copper cables with fiber optic cables to connect two buildings 500 meters apart. Which type of fiber optic cable is best suited for this distance and provides the highest bandwidth over long distances?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Single-mode fiber. Single-mode fiber is designed for long-distance, high-bandwidth applications. Its small core eliminates modal dispersion, allowing signals to travel many kilometers without significant loss. Multimode fiber is limited to shorter distances, typically within a campus or data center. Copper cables cannot reach 500 meters at high speeds. Thus, single-mode fiber is the best choice for connecting two buildings 500 meters apart.

Answer

Coaxial cable

Answer

Multimode fiber

Answer

Cat 6a twisted pair

Question 2

A network engineer is configuring a Cisco switch and needs to ensure that only the MAC address 00:1A:2B:3C:4D:5E is allowed to communicate through interface GigabitEthernet0/1. The engineer enters the command 'switchport port-security mac-address 00:1A:2B:3C:4D:5E' on the interface. However, the switch rejects the command. What is the most likely cause?

Accepted Answer

Port security has not been enabled on the interface with the 'switchport port-security' command.. Port security must be enabled on an interface before specific secure MAC addresses can be configured. The command 'switchport port-security' activates the feature, allowing subsequent commands like 'switchport port-security mac-address' to be accepted. Without this step, the switch rejects attempts to add secure MAC addresses, as the feature is not active on that port.

Answer

The MAC address format is incorrect; Cisco switches require dot notation.

Answer

The interface is currently in trunk mode, and port security requires access mode.

Answer

Port security must be enabled globally before configuring MAC addresses.

Question 3

A user reports that they cannot access any websites by name, but they can reach them by typing the IP address directly into the browser. The technician confirms that the workstation has a valid IP address, subnet mask, and default gateway. Which command should the technician use to test whether the DNS server is responding to queries?

Accepted Answer

nslookup. The ability to reach websites by IP address but not by name strongly suggests a DNS resolution problem. The nslookup command directly queries the DNS server, allowing the technician to confirm whether the server is reachable and resolving names correctly. If nslookup fails, the technician can then investigate DNS server configuration or network connectivity to the DNS server.

Answer

tracert 8.8.8.8

Answer

ping 8.8.8.8

Answer

ipconfig /release

Question 4

A network technician is investigating why a user cannot access a file server at 10.1.1.100. The user's workstation can ping the server successfully, but when the user tries to open a shared folder, the connection times out. The technician verifies that other users can access the same share. Which tool should the technician use to determine if a firewall is blocking the specific file-sharing protocol?

Accepted Answer

telnet 10.1.1.100 445. Successful ping proves IP reachability, but file sharing uses TCP ports such as 445 or 139. A firewall could block those ports while allowing ICMP. Testing TCP port 445 with telnet determines whether the SMB service is reachable. If telnet fails, a firewall or service problem is indicated; if it succeeds, the issue may be at the application or authentication layer.

Answer

tracert 10.1.1.100

Answer

ping 10.1.1.100 -t

Answer

nslookup 10.1.1.100

Question 5

A network administrator is troubleshooting a switch port that connects to a user's PC. The port shows a status of 'err-disabled' and the reason is 'psecure-violation.' Which action should the administrator take first to resolve this?

Accepted Answer

Remove the unauthorized device or MAC address causing the port security violation.. The 'psecure-violation' reason indicates that port security has detected an unauthorized MAC address on the interface. The administrator must first identify and remove the device or MAC address causing the violation, or adjust the port security configuration if the device is legitimate. Simply re-enabling the port without resolving the violation will cause it to become err-disabled again.

Answer

Shut down and re-enable the interface with the shutdown and no shutdown commands.

Answer

Configure the port as a trunk to allow multiple MAC addresses.

Answer

Replace the Ethernet cable connecting the PC to the switch port.

Question 6

A user at a branch office reports that when they browse to their bank's website, the browser displays a certificate warning and the address bar shows a lock with a red line through it. The help desk confirms the user's PC has the correct date and time. Which security concept is MOST likely being violated in this scenario?

Accepted Answer

Authenticity of the website's identity. A browser certificate warning means the TLS certificate presented by the site could not be validated against a trusted certificate authority, the hostname did not match, or the certificate is expired or revoked. Because the user's system clock is correct, the failure points to the authenticity of the website's identity, which is the security property that digital certificates are designed to guarantee.

Answer

Data integrity of the website content

Answer

Confidentiality of the user's credentials

Answer

Availability of the banking web service

Question 7

A network technician is troubleshooting a workstation that cannot reach any resources on a remote subnet. The workstation can ping its default gateway and other hosts on the local subnet. The technician runs 'tracert' from the workstation to a remote server and sees the first hop (the default gateway) respond, but all subsequent hops time out. Which is the most likely cause?

Accepted Answer

The default gateway is missing a route to the remote subnet.. The workstation can reach its default gateway and local subnet, so local configuration and Layer 1-3 connectivity are fine. The traceroute shows the gateway responding but no further hops, indicating the gateway cannot forward packets to the remote subnet. This is consistent with a missing route on the gateway. An incorrect subnet mask or DNS issue would not produce this exact pattern, and a remote firewall would not stop intermediate hops from responding.

Answer

The workstation's DNS server is unreachable.

Answer

A firewall on the remote server is blocking ICMP echo requests.

Answer

The workstation has an incorrect subnet mask.

Question 8

A technician is investigating why a user cannot access a web server at 10.1.1.50. The technician runs 'ping 10.1.1.50' and receives a reply, but when the user tries to access the web server via its hostname 'intranet.corp.local', it fails. The user's workstation has a DNS server configured as 10.1.1.10. Which command should the technician use to verify DNS resolution?

Accepted Answer

nslookup intranet.corp.local. Since the IP address is reachable but the hostname fails, the problem is name resolution. The nslookup command directly queries the DNS server and shows whether it can resolve intranet.corp.local to the correct IP. This isolates the failure to DNS rather than network connectivity, allowing the technician to further investigate the DNS server or its records.

Answer

ipconfig /all

Answer

arp -a

Answer

tracert 10.1.1.50

Question 9

A network administrator is troubleshooting a connectivity issue between two switches connected via a trunk link. The administrator notices that the trunk link is up, but VLAN 10 traffic is not passing. The administrator runs the show interfaces trunk command and sees that VLAN 10 is not listed in the 'VLANs allowed and active in management domain' output. What is the most likely cause?

Accepted Answer

VLAN 10 is not allowed on the trunk port.. The show interfaces trunk command displays the VLANs allowed and active on a trunk. If VLAN 10 is missing from that list, it means the trunk configuration is not permitting VLAN 10. The administrator must use the switchport trunk allowed vlan add 10 command to include it. Other issues like missing VLAN creation or native VLAN mismatch would not cause the VLAN to be absent from the allowed list.

Answer

The native VLAN is mismatched on the trunk.

Answer

VLAN 10 is not created on the switches.

Answer

Spanning Tree Protocol is blocking VLAN 10 on the trunk.

Question 10

A technician is troubleshooting a workstation that can reach servers on the local subnet but cannot reach any host on a remote subnet. The workstation's IP address, subnet mask, and DNS server are correct, and pinging the default gateway succeeds. Which command should the technician use to verify the workstation's default gateway and interface configuration?

Accepted Answer

ipconfig /all. When a host can reach its local subnet and its gateway but nothing beyond, the fault usually lies in the default gateway value, the subnet mask, or the routing configuration on the gateway itself. ipconfig /all shows the complete interface configuration on a Windows client, including the default gateway and subnet mask, which are the values most likely to be misconfigured in this scenario.

Answer

route print

Answer

netstat -ano

Answer

nslookup

Question 11

A network administrator is troubleshooting a Cisco Catalyst switch where a host connected to port Gi1/0/10 is experiencing intermittent connectivity. The administrator suspects a physical layer issue. Which TWO commands would provide the most direct evidence of physical layer problems on that interface? (Choose two.)

Accepted Answer

show controllers ethernet-controller Gi1/0/10 phy. Physical layer problems are best diagnosed by examining interface error counters and PHY-level statistics. The 'show interfaces' command reveals CRC errors, runts, giants, and input errors that indicate cabling or hardware issues. The 'show controllers ethernet-controller phy' command provides deeper physical layer diagnostics, including signal quality. Commands like 'show mac address-table', 'show ip interface brief', and 'show vlan brief' focus on Layer 2/3 configuration and status, not physical layer error conditions.

Answer

show mac address-table interface Gi1/0/10

Answer

show vlan brief

Answer

show ip interface brief

Question 12

A network engineer is deploying a wireless network in a warehouse with metal shelving and forklifts. Users report intermittent connectivity and slow speeds. Which phenomenon is most likely causing the signal degradation?

Accepted Answer

Multipath interference. In a warehouse with metal shelving and moving forklifts, radio signals reflect off these surfaces, creating multiple paths to the receiver. This multipath interference causes signal fading, distortion, and intermittent connectivity. Channel overlap is a configuration issue, attenuation is gradual signal loss, and EMI from forklifts is less likely. Therefore, multipath interference is the most probable cause of the reported problems.

Answer

Attenuation

Answer

Electromagnetic interference

Answer

Channel overlap

Question 13

A network administrator is reviewing the MAC address table on a Cisco access switch and notices that the same MAC address appears on two different access ports in the same VLAN. The administrator confirms that the device with that MAC address is connected to only one port. What is the most likely cause of this duplicate entry?

Accepted Answer

A switching loop exists in the VLAN, causing frames to be learned on multiple ports as they circulate.. A duplicate MAC address entry on two ports in the same VLAN is a classic symptom of a Layer 2 switching loop. Frames circulate through the redundant path, and the switch learns the device's MAC address from frames arriving on different ports. Spanning Tree Protocol normally prevents this by blocking redundant links, so the administrator should verify STP operation and check for unauthorized devices creating loops.

Answer

The device is using a virtual MAC address for redundancy, so the switch learns it on every port in the VLAN.

Answer

The MAC address table has reached its aging time and is flushing entries faster than they can be relearned.

Answer

Port security has been configured with a sticky MAC address, which copies the address to all ports in the VLAN.

Question 14

A network technician is troubleshooting a connectivity issue between two switches. The link between them is up, but users on one switch cannot reach devices on the other. The technician suspects a VLAN mismatch. Which command should be used on a Cisco switch to verify the VLAN assignments on a specific interface?

Accepted Answer

show interfaces switchport. A VLAN mismatch between switches typically occurs when the trunk link does not allow the required VLANs or when access ports are assigned to different VLANs. The show interfaces switchport command provides a comprehensive view of the switchport configuration, including access VLAN, trunk native VLAN, and allowed VLANs. By comparing the output on both switches, the technician can quickly identify and correct any mismatch.

Answer

show vlan brief

Answer

show ip interface brief

Answer

show mac address-table

Question 15

A technician is deploying a new Cisco switch in a wiring closet and needs to connect it to a distribution switch so that it can carry traffic for VLAN 5, VLAN 15, and VLAN 25 between the two devices. The link must carry frames from all three VLANs simultaneously. Which type of port configuration should be applied to the uplink interface on both switches?

Accepted Answer

A trunk port using 802.1Q encapsulation, which tags frames so multiple VLANs can traverse the single link.. To carry traffic for multiple VLANs across a single physical link between switches, the interface must be configured as a trunk using 802.1Q encapsulation. The trunk tags each frame with its VLAN identifier, keeping VLAN 5, VLAN 15, and VLAN 25 traffic logically separate while sharing the uplink. Access, routed, and SVI configurations each fail to provide this multi-VLAN transport.

Answer

A routed port with an IP address on each VLAN subnet, because routing is required to carry multiple VLANs.

Answer

An access port assigned to VLAN 5, because the native VLAN will automatically carry the other VLANs.

Answer

A switch virtual interface for each VLAN, because SVIs automatically extend VLANs across physical links.