100-150 Standards and Concepts — 25 Questions

Question 1

A network engineer is designing a small branch office and needs to select a subnet mask that provides exactly 62 usable host addresses for a single VLAN. Which CIDR notation should the engineer apply to the network prefix?

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

Accepted Answer

/26. A /26 subnet mask (255.255.255.192) leaves 6 host bits, yielding 2^6 = 64 total addresses, of which 62 are usable after reserving the network and broadcast addresses. This exactly matches the requirement of 62 usable host addresses for a single VLAN. The /26 prefix is the correct CIDR notation for this design.

Answer

/25

Answer

/27

Answer

/24

Question 2

A technician is observing a network where many devices are experiencing slow performance and frequent packet collisions. Upon inspection, the technician finds that several desktop computers are connected to an old 8-port Ethernet hub. Why would replacing the hub with a switch resolve this issue?

Accepted Answer

A switch breaks the network into multiple collision domains.. While the explanation correctly identifies that switches provide dedicated bandwidth, it incorrectly states that the transition 'eliminates collision domains'. In reality, a switch creates a separate collision domain for each port, rather than eliminating them entirely.

Answer

A switch will provide a unique IP address to each device automatically.

Answer

A switch uses CSMA/CD to manage traffic more effectively than a hub.

Answer

A switch converts the electrical signals into optical signals for faster speed.

Question 3

Which THREE of the following are considered advantages of the IPv6 protocol over IPv4? (Choose three.)

Accepted Answer

Larger address space. While IPsec was originally designed to be a mandatory component of IPv6 in RFC 2460, this requirement was removed in the updated IPv6 specification (RFC 8200). IPsec is now optional for IPv6, just as it is for IPv4. The other two options (Larger address space and Simplified header structure) are correct, but the inclusion of 'Mandatory IPsec' as a correct answer is factually outdated and misleading for a modern networking exam.

Answer

Broadcast-based address resolution

Answer

Mandatory IPsec implementation

Answer

Compatibility with IPv4 hardware

Question 4

A network architect is evaluating IPv6 address types for a new deployment. The architect needs to identify which TWO IPv6 address types are used for one-to-many communication, where a single packet is sent to multiple destinations. (Choose two.)

Accepted Answer

Anycast. Multicast and anycast are the two IPv6 address types that support one-to-many communication. Multicast delivers a single packet to multiple interfaces that have joined a multicast group. Anycast delivers a packet to the nearest interface among a group of interfaces sharing the same anycast address. Both are essential for IPv6 operations and replace the broadcast concept from IPv4.

Answer

Unicast

Answer

Link-local

Answer

Broadcast

Question 5

A technician is installing a new wireless access point in a small office. The office uses a private IPv4 addressing scheme. The technician needs to assign an IP address to the access point's management interface. Which of the following IP addresses is a private IPv4 address that can be used without conflicting with public internet addresses?

Accepted Answer

192.168.1.1. The private IPv4 address ranges are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. Among the options, 192.168.1.1 is a valid private address commonly used for management interfaces. 172.15.1.1 is public, 224.0.0.1 is multicast, and 10.0.0.1 is also private but the question likely expects the most typical choice for a small office access point, which often defaults to 192.168.1.1.

Answer

10.0.0.1

Answer

172.15.1.1

Answer

224.0.0.1

Question 6

A network engineer is comparing IPv4 and IPv6 header fields. The engineer needs to identify two fields that are present in the IPv6 header but not in the IPv4 header. Which two fields are these? (Choose two.)

Accepted Answer

Flow Label. The IPv6 header introduces the Flow Label and Next Header fields, which are not present in IPv4. The Flow Label is used for flow identification, and the Next Header replaces the Protocol field but is more versatile, supporting extension headers. Traffic Class, Payload Length, and Hop Limit have counterparts in IPv4 (ToS, Total Length, TTL), so they are not unique to IPv6.

Answer

Payload Length

Answer

Traffic Class

Answer

Hop Limit

Question 7

A network administrator is troubleshooting a connectivity issue between two hosts on the same IPv4 subnet. Host A has IP address 192.168.10.10/24 and Host B has 192.168.10.20/24. Host A can ping Host B, but Host B cannot ping Host A. The administrator checks the ARP cache on both hosts and finds that Host B has an entry for Host A, but Host A has no entry for Host B. What is the most likely cause?

Accepted Answer

Host A has a static ARP entry or ARP cache issue that prevents it from learning Host B's MAC address.. Host B can ping Host A because it has a valid ARP entry for Host A and can send frames to it. Host A cannot ping Host B because it lacks an ARP entry for Host B, likely due to a static ARP entry or cache problem. Correcting Host A's ARP cache should restore bidirectional connectivity.

Answer

Host A has an incorrect default gateway, so it cannot reply to Host B's ARP request.

Answer

Host A has a firewall rule blocking ICMP echo replies from Host B.

Answer

Host B has an incorrect subnet mask, causing it to send ARP requests for Host A to the wrong subnet.

Question 8

A network technician is troubleshooting a connectivity issue where a workstation can communicate with local devices but cannot access any resources on a different subnet. After verifying the IP address and subnet mask, which component should be investigated next to ensure the packet can leave the local segment?

Accepted Answer

The default gateway address configured on the workstation.. The default gateway is the router interface that forwards packets destined for remote subnets. If the workstation's default gateway is missing, incorrect, or unreachable, the packet cannot leave the local segment even though local communication works. Since IP and subnet mask are verified, the next logical check is the gateway configuration.

Answer

The MAC address table of the local access switch.

Answer

The physical layer integrity of the crossover cable.

Answer

The DNS server settings for name resolution.

Question 9

An organization is upgrading its cabling infrastructure to support Gigabit Ethernet over a distance of 85 meters. Which twisted-pair cable category is the minimum requirement to reliably support 1000 Mbps speeds at this specific distance?

Accepted Answer

Category 5e (Cat5e). Selecting the correct copper cabling category is vital for meeting bandwidth requirements while adhering to distance limitations defined by TIA/EIA standards. Understanding the capabilities of different categories ensures that the network infrastructure can support modern data rates without signal degradation or excessive crosstalk, which could lead to retransmissions and degraded user experiences across the enterprise.

Answer

Category 3 (Cat3)

Answer

Category 5 (Cat5)

Answer

Category 2 (Cat2)

Question 10

Which TWO characteristics distinguish the User Datagram Protocol (UDP) from the Transmission Control Protocol (TCP)?

Accepted Answer

UDP provides connectionless communication without a handshake.. The choice between TCP and UDP is a fundamental architectural decision based on the needs of the application. TCP provides reliability and flow control at the cost of overhead, while UDP prioritizes speed and efficiency. Understanding these differences allows network professionals to troubleshoot performance issues and optimize traffic for different types of data, such as streaming or file transfers.

Answer

UDP uses sequence numbers to reassemble data in the correct order.

Answer

UDP operates at the Network Layer of the OSI model.

Answer

UDP includes a three-way handshake to ensure delivery.

Question 11

Which THREE statements accurately describe the functions of a Layer 2 switch in a local area network?

Accepted Answer

Switches use MAC addresses to make forwarding decisions.. Layer 2 switches are the workhorses of local networks, providing high-speed connectivity by managing frame delivery. Unlike hubs, switches use hardware-based logic to segment the network and optimize traffic flow. Understanding how they build address tables and handle different types of traffic is essential for any technician responsible for maintaining or troubleshooting enterprise network infrastructure and ensuring data reaches its intended destination.

Answer

Switches route traffic between different VLANs using IP addresses.

Answer

Switches perform deep packet inspection to filter malicious traffic.

Question 12

A network administrator is implementing IPv6 in a corporate environment. Which TWO address types are commonly used to facilitate local link communication and global internet access respectively?

Accepted Answer

Link-Local Address (FE80::/10). Option A, the Link-Local Address (FE80::/10), is correct because every IPv6-enabled interface automatically configures a link-local address within the FE80::/10 prefix, which is used for communication on the local segment only (neighbor discovery, router solicitation, and next-hop resolution) and is never routed beyond the link. Option C, the Global Unicast Address (2000::/3), is correct because this is the range from which globally routable IPv6 addresses are allocated, allowing hosts to communicate across the public internet. Option B, the Unique Local Address (FC00::/7), is not correct here because it is designed for private, non-internet-routed communication within an organization, not global internet access. Option D, the Multicast Address (FF00::/8), is not correct because it identifies groups of interfaces for one-to-many delivery rather than providing local link or global unicast communication. Option E, the Loopback Address (::1/128), is not correct because it is used only for a node to send traffic to itself, not for link or internet communication.

Answer

Unique Local Address (FC00::/7)

Answer

Multicast Address (FF00::/8)

Answer

Loopback Address (::1/128)

Question 13

Which layer of the OSI model is responsible for determining the best physical path for data to travel across multiple interconnected networks using logical addressing?

Accepted Answer

Network Layer (Layer 3). The Network Layer is a pivotal part of the OSI model, focusing on the movement of data between different networks. It utilizes logical addresses, such as IP addresses, to identify source and destination hosts. Routers operate at this layer, maintaining routing tables and using protocols to find the most efficient path for data, which is essential for global connectivity.

Answer

Data Link Layer (Layer 2)

Answer

Transport Layer (Layer 4)

Answer

Physical Layer (Layer 1)

Question 14

What is the primary function of the Address Resolution Protocol (ARP) in an IPv4 network?

Accepted Answer

It maps a known IPv4 address to a corresponding MAC address.. ARP (Address Resolution Protocol) is used when a host knows the IPv4 address of a destination on the same local network but needs the corresponding MAC address to build the Layer 2 frame. The host broadcasts an ARP request asking 'Who has IP X? Tell MAC Y,' and the owner of that IP replies with its MAC address. This mapping is then cached in the ARP table for future use.

Answer

It maps a known MAC address to a dynamically assigned IP address.

Answer

It translates human-readable domain names into numerical IP addresses.

Answer

It provides a secure encrypted tunnel for data transmission between hosts.

Question 15

Which TWO protocols are commonly used to retrieve email from a remote server to a local mail client?

Accepted Answer

Post Office Protocol version 3 (POP3). Email retrieval protocols allow users to access their messages stored on a central server. POP3 and IMAP4 are the industry standard protocols for this task, each offering different levels of synchronization and storage management. Understanding these protocols is essential for configuring client devices and troubleshooting mail delivery issues in a corporate or personal network environment.

Answer

Simple Mail Transfer Protocol (SMTP)

Answer

Hypertext Transfer Protocol (HTTP)

Answer

File Transfer Protocol (FTP)

Question 16

Which field in an IPv4 header is used to prevent a packet from circulating indefinitely in the event of a routing loop?

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 at each router hop. When it reaches zero, the router discards the packet and sends an ICMP Time Exceeded message back to the source, preventing packets from looping forever in the event of a routing loop.

Answer

Protocol Field

Answer

Header Checksum

Answer

Differentiated Services (DiffServ)

Question 17

A user is unable to reach 'cisco.com' in their web browser but can successfully ping the IP address '72.163.4.161'. Which network service is most likely failing or misconfigured?

Accepted Answer

Domain Name System (DNS). This scenario highlights the distinction between basic connectivity and name resolution. If a user can reach a destination by IP but not by name, the underlying network path is functional, but the translation service is broken. Diagnosing DNS issues is a daily task for technicians, as it is often the root cause of 'internet is down' complaints when the connection is actually active.

Answer

Dynamic Host Configuration Protocol (DHCP)

Answer

Network Address Translation (NAT)

Answer

Address Resolution Protocol (ARP)

Question 18

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 19

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 20

Refer to the exhibit. An administrator observes that interface Gig0/1 is in 'up' status but experiences high latency and interface errors. Based on the provided configuration, what is the most likely cause?

Accepted Answer

The interface is set to auto-negotiate, causing a duplex mismatch.. An interface that is 'up' but shows high latency and errors typically indicates a duplex mismatch, which occurs when one side is hard-set to full duplex and the other auto-negotiates to half duplex. This causes collisions, late collisions, FCS errors, and degraded throughput. The exhibit's configuration showing auto-negotiation on one side and a fixed setting on the other confirms this scenario.

Answer

The cable is faulty.

Answer

The interface is administratively shut down.

Answer

The bandwidth is too low for traffic.