100-150 Practice Test 12 — 15 Questions

Question 1

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?

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

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 2

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 3

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 4

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 5

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.

Question 6

A network administrator is documenting the OSI model layers for a training manual. The administrator needs to identify which OSI layer is responsible for establishing, managing, and terminating sessions between applications on different hosts. Which OSI layer should be documented?

Accepted Answer

Session layer. The Session layer is specifically tasked with setting up, coordinating, and tearing down conversations between applications. It provides mechanisms for dialogue control and synchronization, which are distinct from the transport functions of Layer 4 or the data formatting of Layer 6. Documenting this layer accurately reflects its role in managing sessions between hosts.

Answer

Application layer

Answer

Transport layer

Answer

Presentation layer

Question 7

Which TWO functions are performed by a Cisco switch at the Data Link layer? (Choose two.)

Accepted Answer

Forwarding frames based on destination MAC addresses. Option B is correct because a Cisco switch operates at Layer 2 and forwards frames by looking up the destination MAC address in its MAC address table to select the correct egress port. Option C is correct because the switch learns source MAC addresses from the ingress frames it receives and records them along with the receiving port in its MAC address table, which builds the basis for future forwarding decisions. Option A is incorrect because best-path calculation based on IP addresses is a Layer 3 routing function performed by routers, not switches. Option D is incorrect because translating between different network topologies is not a standard Data Link layer switch function; such translation is typically handled by gateways or specific translation devices. Option E is incorrect because encapsulating data packets into segments is a Layer 4 (Transport layer) function, such as TCP or UDP segmentation, not a switch operation.

Answer

Calculating the best path based on IP addresses

Answer

Translating between different network topologies

Answer

Encapsulating data packets into segments

Question 8

Which TWO statements correctly describe valid rules for compressing or representing IPv6 addresses?

Accepted Answer

Leading zeros in a quartet can be omitted.. Option A is correct because RFC 4291 permits omitting leading zeros within any 16-bit hexadecimal quartet, so '0db8' can be written as 'db8' and '0001' as '1'. Option B is correct because the '::' shorthand may be used only once in an address; it represents one or more consecutive groups of zeros, and using it twice would make the address ambiguous. Option C is wrong because only leading zeros may be dropped, not trailing zeros, since removing trailing zeros would change the value of the quartet. Option D is wrong because compression is optional, not mandatory, and a single '0000' quartet may be written as '0' or left uncompressed. Option E is wrong because IPv6 uses colons to separate quartets, while dots appear only in mixed IPv4-embedded notation such as '::ffff:192.168.0.1'.

Answer

Trailing zeros in a quartet can be omitted to save space.

Answer

A single quartet of '0000' must always be compressed to '::'.

Answer

IPv6 addresses use dots to separate quartets for better readability.

Question 9

Which THREE factors influence the selection of a specific router interface for traffic forwarding? (Choose three.)

Accepted Answer

Longest prefix match. The router selects a forwarding interface through a two-stage process: first it narrows candidate routes using the longest prefix match (Option A), so the route with the most specific matching network prefix wins over less specific ones. If multiple routes to the same destination prefix are learned from different sources, administrative distance (Option C) breaks the tie by preferring the more trustworthy source (e.g., connected, static, or a given routing protocol). Among routes from the same source/protocol, the metric value (Option D) is compared, and the lowest metric determines the best path and thus the egress interface. The source MAC address (Option B) is a Layer 2 field used for frame delivery and MAC address-table lookups, not for choosing a route or egress interface. The switching fabric capacity (Option E) is an internal hardware throughput characteristic of the device and does not participate in route or interface selection.

Answer

Source MAC address

Answer

Switching fabric capacity

Question 10

A network technician is troubleshooting a connectivity issue. The technician suspects that a router is not forwarding packets correctly because the Time to Live (TTL) value in the IP header is being decremented to zero. Which field in the IPv4 header is responsible for this decrementing behavior and the subsequent discarding of the packet?

Accepted Answer

Time to Live (TTL) field. The TTL field is designed to limit the lifespan of a packet. Each router that forwards the packet decrements the TTL by one. If the TTL reaches zero, the router drops the packet and may send an ICMP Time Exceeded message. This prevents infinite loops and is the exact mechanism the technician suspects.

Answer

Header Checksum field

Answer

Identification field

Answer

Protocol field

Question 11

A technician is documenting the OSI model for a training manual and needs to identify which layer is responsible for logical addressing and path determination between networks. Which OSI layer performs this function?

Accepted Answer

Network layer (Layer 3). The Network layer is responsible for logical addressing and routing, which are essential for moving data between different networks. Routers use IP addresses at this layer to determine the best path. The other layers handle different functions: Data Link uses MAC addresses, Transport ensures reliable delivery, and Session manages connections.

Answer

Session layer (Layer 5)

Answer

Data Link layer (Layer 2)

Answer

Transport layer (Layer 4)

Question 12

A small office technician is assigning IPv4 addresses to devices on a network that will not connect to the internet and uses the 192.168.50.0/24 range. The technician needs to pick an address from the valid host range for this network. Which address should the technician choose?

Accepted Answer

192.168.50.1. For any subnet, the network address and the broadcast address are reserved and cannot be assigned to hosts. In 192.168.50.0/24, the usable host range is 192.168.50.1 through 192.168.50.254, so the only valid host address listed is 192.168.50.1. The address ending in .0 is the network, .255 is the broadcast, and 192.168.51.1 is in a different subnet.

Answer

192.168.50.255

Answer

192.168.50.0

Answer

192.168.51.1

Question 13

A network administrator is reviewing the OSI model layer responsibilities. The administrator needs to identify which layer is responsible for establishing, managing, and terminating sessions between applications on different hosts. Which OSI layer performs this function?

Accepted Answer

Session layer. The Session layer is specifically tasked with setting up, maintaining, and ending sessions between applications. It provides dialog control and synchronization, which are essential for managing ongoing communications. The other layers have different primary functions: Transport ensures reliable data transfer, Presentation formats data, and Application provides services to users. Thus, the Session layer is the correct answer for session management.

Answer

Application layer

Answer

Transport layer

Answer

Presentation layer

Question 14

A network administrator is configuring a switch port for a server that must be reachable by multiple VLANs without routing through an external router. Which feature should be configured on the switch port?

Accepted Answer

Trunk port. A trunk port uses VLAN tagging to carry traffic for multiple VLANs over a single link. This allows a server with a VLAN-aware network interface to communicate on multiple VLANs without an external router. Access ports support only one VLAN, Spanning Tree prevents loops, and port mirroring is for monitoring.

Answer

Access port

Answer

Spanning Tree Protocol

Answer

Port mirroring

Question 15

A technician is documenting the TCP/IP model for a training manual. The manual must describe the layer that is responsible for logical addressing and routing of packets between different networks. Which layer of the TCP/IP model performs this function?

Accepted Answer

Internet layer. In the TCP/IP model, the Internet layer corresponds to the OSI network layer and handles logical addressing and routing. IP addresses are assigned at this layer, and routers use them to forward packets between networks. The other layers handle local framing, end-to-end transport, or application services, so they do not perform the described function.

Answer

Transport layer

Answer

Application layer

Answer

Network Access layer