100-150 Practice Test 5 — 25 Questions

Question 1

A small branch office has a Cisco Layer 2 access switch with three access ports assigned to VLAN 10 for the sales team and two access ports assigned to VLAN 20 for the finance team. The finance team reports that they cannot reach the sales team's shared file server, even though both teams are connected to the same physical switch. No router or Layer 3 switch is deployed at this branch. What is the most likely explanation for the connectivity failure?

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

Accepted Answer

VLAN 10 and VLAN 20 are separate broadcast domains, and inter-VLAN traffic requires a Layer 3 device that is not present in this topology.. Because VLANs are independent broadcast domains, hosts in VLAN 10 and VLAN 20 cannot exchange traffic at Layer 2 even when they are attached to the same physical switch. Communication between VLANs requires a Layer 3 device to route packets between the subnets. With only a Layer 2 access switch in the branch, no such device exists, so the finance team cannot reach the sales server.

Answer

The switch needs the ip routing global configuration command enabled so that it can forward frames between VLAN 10 and VLAN 20.

Answer

The access ports must be configured as trunk ports so that frames from both VLANs can be carried between them.

Answer

Spanning Tree Protocol has blocked the redundant path between the two VLANs, preventing traffic from flowing between them.

Question 2

Which type of cabling is best suited for long-distance data transmission that requires high bandwidth and is immune to electromagnetic interference?

Accepted Answer

Single-mode Fiber. Fiber-optic cabling uses light pulses to transmit data, providing immense bandwidth over long distances without being affected by electromagnetic interference (EMI). This makes it superior to copper-based media for backbone connections. Understanding the differences between fiber and copper is crucial for planning infrastructure, especially in environments where cable runs exceed standard Ethernet limits or require high-speed data integrity across large facilities.

Answer

Unshielded Twisted Pair (UTP)

Answer

Coaxial Cable

Answer

Shielded Twisted Pair (STP)

Question 3

A host with the IP address 192.168.1.50 and a subnet mask of 255.255.255.0 is attempting to send data to a server at 10.1.1.5. Which address must be configured on the host to allow the data to exit the local subnet?

Accepted Answer

Default Gateway. The host 192.168.1.50/24 and the server 10.1.1.5 are on different subnets, so the host cannot ARP for the server directly. It must forward the frame to its default gateway, which is the router interface on the local subnet that knows how to reach remote networks. Without a default gateway, the host can only communicate with devices in 192.168.1.0/24.

Answer

DNS Server Address

Answer

Loopback Address

Answer

Broadcast Address

Question 4

A network engineer is configuring IPv6 on a Cisco router interface. The engineer wants to ensure that the interface can automatically generate a link-local address and participate in neighbor discovery without manual configuration. Which IPv6 address type is automatically generated on the interface when IPv6 is enabled?

Accepted Answer

Link-local address. Enabling IPv6 on an interface automatically creates a link-local address, which is essential for neighbor discovery and local link communication. Global unicast and unique local addresses require additional configuration or router advertisements. Multicast addresses are not unicast addresses assigned to the interface.

Answer

Unique local address

Answer

Multicast address

Answer

Global unicast address

Question 5

Refer to the exhibit. An administrator is reviewing the interface configuration. Which statement regarding these subnets is true?

Accepted Answer

The subnets are contiguous and correctly separated by 16 addresses each.. The exhibit shows three interfaces configured with /28 masks. A /28 mask provides 16 IP addresses per block. The first subnet is 172.16.5.0, the second is 172.16.5.16, and the third is 172.16.5.32. Because each interface is assigned the first host address of its respective block, the configuration is valid and follows classless inter-domain routing principles for non-overlapping subnets.

Answer

The subnets overlap, causing a routing conflict.

Answer

The configuration will fail because the IP addresses are not on the same network.

Answer

The mask /28 is invalid for these specific IP addresses.

Question 6

Which security threat involves an attacker sending unsolicited and massive amounts of traffic to a network service to make it unavailable to legitimate users?

Accepted Answer

Denial of Service. Denial of Service (DoS) attacks focus on exhausting system resources or bandwidth. By overwhelming a target, the attacker prevents legitimate traffic from reaching the intended service. Understanding this threat is crucial for engineers who must implement traffic shaping, rate limiting, and ACLs to mitigate the impact of such attacks, thereby preserving the availability and reliability of critical network services for authorized users.

Answer

Phishing

Answer

Man-in-the-Middle

Answer

MAC Spoofing

Question 7

Which field in the IPv4 header is primarily responsible for preventing a packet from looping indefinitely in a network?

Accepted Answer

Time-to-Live (TTL). The Time-to-Live (TTL) field in the IPv4 header is an 8-bit value that is decremented by one each time a packet passes through a router. When TTL reaches zero, the router discards the packet and sends an ICMP Time Exceeded message back to the source. This mechanism prevents packets from looping indefinitely due to routing loops or misconfigurations.

Answer

Protocol

Answer

Fragment Offset

Answer

Header Checksum

Question 8

Refer to the exhibit. What can be determined about the status of interface FastEthernet 0/1?

Accepted Answer

The interface is working correctly at the physical and data link layers.. The output shows the interface is administratively up and the line protocol is up, indicating a functional physical link with an active Layer 2/3 configuration. This is the ideal state for a production interface. Being able to interpret 'show ip interface brief' is a mandatory skill for quickly diagnosing whether issues are physical, configuration-related, or protocol-based in enterprise network troubleshooting scenarios.

Answer

The interface is disabled and needs to be enabled.

Answer

The interface has no IP address assigned to it.

Answer

There is a physical layer problem preventing connectivity.

Question 9

A network technician is tasked with dividing the 192.168.10.0/24 network into four equal-sized subnets to accommodate different departments. Which subnet mask should be applied to achieve this requirement, and how many usable host addresses will be available in each subnet?

Accepted Answer

255.255.255.192 with 62 hosts. To divide a /24 network into four equal subnets, you must borrow two bits from the host portion, changing the prefix from /24 to /26. A /26 prefix corresponds to a subnet mask of 255.255.255.192. Each resulting subnet contains 64 total addresses, but subtracting the network ID and broadcast address leaves 62 usable host addresses for devices.

Answer

255.255.255.128 with 126 hosts

Answer

255.255.255.224 with 30 hosts

Answer

255.255.255.240 with 14 hosts

Question 10

Refer to the exhibit. If a frame with a destination MAC address of 0055.4433.2211 arrives on interface FastEthernet 0/1, how will the switch handle the traffic?

Accepted Answer

Flood out Fa0/2. Switches use the MAC address table to make forwarding decisions. When a destination MAC is not found in the table, the switch performs an action known as unknown unicast flooding. It sends the frame out of every port in the same VLAN, except for the port on which the frame was originally received, to locate the destination device.

Answer

Forward to Fa0/2

Answer

Drop the frame

Answer

Update the table

Question 11

An enterprise network administrator needs to deploy a secure out-of-band management network for enterprise switches and routers. Which infrastructure design approach provides the highest level of isolation and security?

Accepted Answer

Deploy a physically separate management network utilizing dedicated management Ethernet ports and an independent access switch infrastructure.. Dedicated management ports combined with an isolated physical switch infrastructure completely separate management traffic from production data paths. This structural isolation ensures that even if user data planes experience severe congestion, storms, or security compromises, administrators retain reliable access to device consoles and management daemons for troubleshooting and remediation.

Answer

Configure a dedicated management VLAN on the primary production access switches with restricted access control lists.

Answer

Implement Virtual Routing and Forwarding instances inside the core routing layer for carrying all administrative terminal sessions.

Answer

Tunnel all interactive administrative SSH sessions through high-priority IP Service Level Agreements and weighted fair queuing.

Question 12

Which THREE features are introduced or enhanced in WPA3 to improve wireless security compared to WPA2? (Choose THREE).

Accepted Answer

Simultaneous Authentication of Equals (SAE). WPA3 is the latest generation of Wi-Fi security, providing significant improvements over WPA2. It addresses several known vulnerabilities, such as offline dictionary attacks and the lack of forward secrecy. Understanding these enhancements is vital for technicians responsible for deploying modern, secure wireless networks that protect sensitive data from sophisticated threats.

Answer

Support for WEP backward compatibility

Answer

TKIP encryption by default

Question 13

A network designer needs to select media for a high-performance backbone that supports at least 10 Gbps. Which THREE media types are capable of supporting this speed? (Choose THREE.)

Accepted Answer

Single-mode fiber. Single-mode fiber (A) is correct because it carries laser-based signals over long distances and easily supports 10 Gbps and far higher rates (10G/40G/100G Ethernet). Multi-mode fiber (C) is correct because OM3/OM4/OM5 multimode supports 10 Gbps Ethernet (e.g., 10GBASE-SR) over typical backbone distances. Category 6a copper (D) is correct because it is specified to support 10GBASE-T at 10 Gbps up to 100 meters. Category 5e (B) is limited to 1 Gbps (1000BASE-T) and does not meet the 10 Gbps requirement, and Category 3 (E) only supports up to 10 Mbps and is unsuitable for a high-performance backbone.

Answer

Category 5e copper

Answer

Category 3 copper

Question 14

An organization is designing a redundant campus distribution layer to ensure high availability and fast failover. Which TWO infrastructure features should be implemented to achieve sub-second convergence and eliminate routing loops? (Choose two)

Accepted Answer

Virtual Switching System or StackWise technology to merge multiple physical switches into a single logical control plane.. Option A is correct because Virtual Switching System (VSS) or StackWise merges multiple physical switches into one logical control plane, enabling Multichassis EtherChannel (MEC) and eliminating the need for Spanning Tree to block redundant links, which removes Layer 2 loops and supports fast, deterministic failover. Option C is correct because Bidirectional Forwarding Detection (BFD) provides sub-second (often 50-300 ms) link failure detection and, when integrated with routing protocols like OSPF, EIGRP, or BGP, triggers rapid reconvergence far faster than default protocol hellos. Option B is not appropriate because classic STP with default 20-second max age and 2-second forward delay yields convergence in tens of seconds, not sub-second, and does not meet the design goal. Option D is not appropriate because UDLD in normal mode only logs unidirectional link conditions without shutting down the interface, so it does not provide fast failover or loop prevention. Option E is not appropriate because static floating routes to secondary ISPs are for WAN/Internet redundancy and do not address campus distribution-layer loop elimination or sub-second convergence.

Answer

Classic Spanning Tree Protocol with default port-cost metrics and standard 20-second maximum age timers.

Answer

Unidirectional Link Detection running in normal mode to log fiber transceiver misbehaviors without interface shutdown.

Answer

Static routing configurations with floating backup routes pointing to secondary internet service providers.

Question 15

A network technician is configuring a new Cisco switch and needs to assign an IP address to the management VLAN interface so the switch can be reached remotely via SSH. The switch currently has no VLAN interfaces configured. Which command must the technician use to create the management interface and enter interface configuration mode?

Accepted Answer

interface vlan 1. To assign a management IP to a Cisco switch, an SVI must be configured. The command interface vlan 1 creates the SVI for VLAN 1 and enters interface configuration mode, where an IP address can be assigned. Physical ports are Layer 2 and cannot hold IP addresses, and the vlan command only creates VLANs, not interfaces.

Answer

vlan 1

Answer

interface fastethernet 0/1

Answer

ip address 192.168.1.10 255.255.255.0

Question 16

A network administrator is troubleshooting an issue where a workstation cannot communicate with a server on a different subnet. The workstation has an IP address of 192.168.1.5/24 and the server is at 192.168.2.10/24. Which component is strictly responsible for routing traffic across these disparate subnets?

Accepted Answer

The router or Layer 3 gateway. Routing traffic between distinct subnets requires a Layer 3 device capable of making forwarding decisions based on destination IP addresses. While switches operate at Layer 2 for local segments, they cannot bridge traffic across different broadcast domains without an inter-VLAN routing interface or a dedicated router. Understanding this boundary is fundamental to network architecture and ensuring proper traffic flow in multi-segment environments.

Answer

The local Layer 2 switch

Answer

The network interface card (NIC)

Answer

The ARP cache on the workstation

Question 17

A network administrator observes that a workstation cannot ping its default gateway. The physical link light is active, and the local IP configuration appears correct. Which diagnostic step should be performed first to isolate the layer 2 connectivity issue?

Accepted Answer

Check the ARP table for the gateway IP address.. Verifying the ARP table is the most effective initial step when IP connectivity fails despite physical link status. It confirms whether the device can successfully resolve the MAC address of the default gateway, which is a prerequisite for layer 3 communication. If the ARP request fails, the issue is likely within the local broadcast domain, such as an incorrect VLAN assignment or a misconfigured trunk port on the connected switch.

Answer

Perform a traceroute to the internet gateway.

Answer

Flush the DNS cache on the workstation.

Answer

Reboot the switch connected to the workstation.

Question 18

Refer to the exhibit. A technician is investigating why a device connected to FastEthernet0/1 cannot communicate. Based on the output, what is the most likely issue?

Accepted Answer

There is a Layer 2 framing or protocol mismatch.. The 'up/down' status on a Cisco interface specifically points to a Layer 2 problem. This means the physical layer (Layer 1) is sensing a signal, but the data link layer (Layer 2) cannot establish a connection. Common causes include encapsulation mismatches, lack of keepalives, or specific protocol failures like spanning-tree blocking the port.

Answer

The cable is disconnected or the remote device is powered off.

Answer

The interface has been manually disabled by an administrator.

Answer

The IP address has not been assigned to the interface.

Question 19

Which device is primarily responsible for performing inter-VLAN routing in a modern enterprise network?

Accepted Answer

Layer 3 Switch. A Layer 3 switch is primarily responsible for performing inter-VLAN routing in modern enterprise networks. It combines the functionality of a switch and a router, allowing it to route traffic between VLANs at wire speed using hardware-based routing. This is more efficient than using a traditional router for inter-VLAN routing.

Answer

Layer 2 Switch

Answer

Hub

Answer

Repeater

Question 20

Which TWO of the following statements accurately describe the characteristics of the OSI model's Data Link layer (Layer 2)? (Choose two.)

Accepted Answer

It handles physical addressing via MAC addresses.. Option B is correct because the Data Link layer (Layer 2) is responsible for physical addressing using MAC addresses, which are burned into network interface cards and used to deliver frames on the local segment. Option D is correct because the IEEE 802 model divides Layer 2 into two sublayers: the Logical Link Control (LLC) sublayer, which handles framing and flow control, and the Media Access Control (MAC) sublayer, which governs access to the shared physical medium. Option A is incorrect because logical addressing via IP headers is a function of the Network layer (Layer 3), not Layer 2. Option C is incorrect because end-to-end delivery across multiple routers is a transport-layer (Layer 4) responsibility, while Layer 2 only handles node-to-node delivery on the same link. Option E is incorrect because path determination and routing are performed by Layer 3 routing protocols, not by the Data Link layer.

Answer

It provides logical addressing through IP protocol headers.

Answer

It manages end-to-end data delivery across multiple routers.

Answer

It determines the best path to reach a remote destination.