CCNA Networking Concepts Questions

29 of 104 questions · Page 2/2 · Networking Concepts · Answers revealed

76
MCQeasy

Which of the following network topologies connects each node to exactly two other nodes, forming a closed loop?

A.Star
B.Bus
C.Ring
D.Mesh
AnswerC

Ring topology connects each node to exactly two neighbors, forming a continuous loop for data transmission.

Why this answer

In a ring topology, each node is connected to exactly two neighbors, forming a closed loop where data travels in one direction (or sometimes dual-ring for redundancy). This is the only topology among the options that inherently creates a circular path with each node having exactly two connections.

Exam trap

The trap here is that candidates often confuse a logical ring (like Token Ring or FDDI) with a physical star-wired ring, where the wiring appears star-shaped but the logical data path is a ring, leading them to incorrectly select 'Star' because they see a central device.

How to eliminate wrong answers

Option A is wrong because a star topology connects all nodes to a central hub or switch, not to exactly two other nodes. Option B is wrong because a bus topology uses a single shared backbone cable where each node taps into the line, and nodes are not connected in a closed loop. Option D is wrong because a mesh topology (full or partial) connects nodes with multiple redundant paths, and each node typically has more than two connections, not exactly two.

77
MCQmedium

Which IPv6 address is reserved for loopback?

A.::1
B.::
C.127.0.0.1
D.2000::/3
AnswerA

::1 is the IPv6 loopback address used to send traffic to itself.

Why this answer

The IPv6 loopback address is ::1 (equivalent to 127.0.0.1 in IPv4). It is used by a host to send traffic to itself without any physical network interface involvement, as defined in RFC 4291. This address is not routable and should never appear outside the host.

Exam trap

The trap here is that candidates confuse the unspecified address (::) with the loopback address (::1), or mistakenly apply the IPv4 loopback concept (127.0.0.1) to IPv6 without recognizing the different notation.

How to eliminate wrong answers

Option B (::) is wrong because it represents the unspecified address, used during Duplicate Address Detection (DAD) or as a source address before a valid address is assigned, not for loopback. Option C (127.0.0.1) is wrong because it is the IPv4 loopback address, not an IPv6 address. Option D (2000::/3) is wrong because it is the global unicast address prefix for routable IPv6 addresses, not reserved for loopback.

78
MCQeasy

A workstation with IP address 10.0.1.5/24 needs to communicate with a server at 10.0.2.10/24. The workstation's default gateway is configured as 10.0.1.1. Which of the following will the workstation do with the IP packets destined for the server?

A.Send the packets directly to the server using ARP.
B.Send the packets to the default gateway.
C.Send the packets to the DNS server for resolution.
D.Drop the packets because the server is on a different network.
AnswerB

Correct. The workstation identifies the destination is on a different subnet and forwards all traffic to the default gateway for routing.

Why this answer

The workstation's IP address (10.0.1.5/24) and the server's IP address (10.0.2.10/24) are on different subnets (10.0.1.0/24 vs. 10.0.2.0/24). When a host determines that the destination is not on the same local network, it will not attempt direct delivery via ARP. Instead, it forwards the IP packet to its configured default gateway (10.0.1.1), which then routes the packet toward the server's subnet.

Exam trap

The trap here is that candidates mistakenly think a host can ARP for any IP address, even across subnets, or that a host will drop traffic to a different subnet without a router, when in fact the host relies on its default gateway to reach remote networks.

How to eliminate wrong answers

Option A is wrong because ARP is used only to resolve the MAC address of a destination on the same local subnet; since the server is on a different subnet, the workstation will not send an ARP request for the server's IP. Option C is wrong because DNS resolution translates hostnames to IP addresses, but the workstation already knows the server's IP address (10.0.2.10) and does not need DNS for forwarding decisions. Option D is wrong because routers (including the default gateway) are designed to forward packets between different subnets; the workstation does not drop packets destined for a different network—it sends them to the gateway.

79
MCQeasy

A technician needs to connect two different networks and forward traffic based on IP addresses. Which of the following devices operates at Layer 3 of the OSI model and should be used?

A.Hub
B.Switch
C.Router
D.Bridge
AnswerC

Routers are Layer 3 devices that forward packets based on IP addresses, enabling communication between different networks.

Why this answer

A router operates at Layer 3 (Network layer) of the OSI model and makes forwarding decisions based on IP addresses. It uses routing tables and protocols such as OSPF or BGP to determine the best path for packets between different networks. This makes it the correct device for connecting two distinct networks and forwarding traffic by IP address.

Exam trap

CompTIA often tests the misconception that a 'multilayer switch' can replace a router for all Layer 3 functions, but the question specifically asks for a device that operates at Layer 3 and forwards based on IP addresses, and a standard switch (even a Layer 3 switch) is still primarily a switch; the correct answer is always the router when the context is connecting different networks.

How to eliminate wrong answers

Option A is wrong because a hub operates at Layer 1 (Physical layer) and simply repeats electrical signals to all ports, with no ability to forward traffic based on IP addresses. Option B is wrong because a switch operates primarily at Layer 2 (Data Link layer) and forwards frames based on MAC addresses, not IP addresses; while some switches support Layer 3 routing, a standard switch does not perform IP-based forwarding between different networks. Option D is wrong because a bridge operates at Layer 2 (Data Link layer) and connects two network segments by forwarding frames based on MAC addresses, not IP addresses.

80
MCQeasy

A network technician is explaining the function of a default gateway to a junior technician. Which of the following best describes the purpose of a default gateway?

A.It connects two different VLANs.
B.It provides DHCP services to the local network.
C.It routes traffic from the local network to external networks.
D.It translates private IP addresses to public IP addresses.
AnswerC

The default gateway is the next-hop router for all traffic destined to networks not in the local routing table. Without it, devices on the local subnet cannot communicate with external IP addresses.

Why this answer

The default gateway is a router or Layer 3 device that serves as the next-hop destination for packets destined to IP addresses outside the local subnet. When a host determines that the destination IP is not on the same network, it forwards the frame to the default gateway's MAC address, which then routes the packet toward the external network. This is defined in RFC 1122 and is essential for any host that needs to communicate beyond its directly connected segment.

Exam trap

CompTIA often tests the misconception that the default gateway performs NAT or DHCP, but the trap here is that candidates confuse the default gateway's routing function with other network services like address translation or dynamic addressing.

How to eliminate wrong answers

Option A is wrong because connecting two different VLANs requires a Layer 3 device (router or multilayer switch) with an interface in each VLAN or using a router-on-a-stick configuration, not a default gateway; the default gateway is a single next-hop address, not a VLAN interconnect. Option B is wrong because DHCP services are provided by a DHCP server (often a dedicated server or a router with DHCP service enabled), not by the default gateway; the default gateway's role is routing, not address assignment. Option D is wrong because translating private IP addresses to public IP addresses is the function of NAT (Network Address Translation), typically performed by a router or firewall, not the default gateway itself; the default gateway is simply the next-hop router for outbound traffic, regardless of whether NAT is applied.

81
MCQeasy

Which of the following network devices operates primarily at Layer 2 of the OSI model and uses MAC addresses to forward data?

A.Hub
B.Switch
C.Router
D.Firewall
AnswerB

A switch forwards frames based on MAC addresses, operating at the data link layer.

Why this answer

A switch operates primarily at Layer 2 (Data Link layer) of the OSI model, forwarding frames based on destination MAC addresses. It builds a MAC address table by learning source MAC addresses from incoming frames and uses this table to make forwarding decisions, reducing collision domains and improving network efficiency.

Exam trap

Cisco often tests the distinction between a switch (Layer 2, MAC-based forwarding) and a router (Layer 3, IP-based forwarding), and the trap here is that candidates may confuse a switch's ability to segment collision domains with routing functionality, or mistakenly think a switch uses IP addresses for forwarding decisions.

How to eliminate wrong answers

Option A is wrong because a hub operates at Layer 1 (Physical layer) and simply repeats electrical signals out all ports, with no MAC address awareness or forwarding logic. Option C is wrong because a router operates at Layer 3 (Network layer) and forwards packets based on IP addresses, not MAC addresses. Option D is wrong because a firewall operates at Layers 3-7 (typically inspecting IP addresses, ports, and application data) and does not forward traffic using MAC addresses as its primary function.

82
MCQeasy

Which of the following protocols is used to automatically assign IP addresses to devices on a network?

A.A) DNS
B.B) DHCP
C.C) ARP
D.D) ICMP
AnswerB

DHCP (Dynamic Host Configuration Protocol) is the correct protocol for automatic IP address assignment.

Why this answer

DHCP (Dynamic Host Configuration Protocol) is the correct answer because it is specifically designed to automatically assign IP addresses and other network configuration parameters (such as subnet mask, default gateway, and DNS servers) to devices on a network. When a client device connects, it sends a DHCP Discover broadcast, and the DHCP server responds with an Offer, followed by a Request and Acknowledgment (DORA process), enabling plug-and-play connectivity.

Exam trap

Cisco often tests the distinction between DHCP (address assignment) and DNS (name resolution), leading candidates to confuse the two because both are essential for network communication, but only DHCP handles automatic IP configuration.

How to eliminate wrong answers

Option A (DNS) is wrong because the Domain Name System resolves human-readable domain names (e.g., www.example.com) to IP addresses; it does not assign IP addresses to devices. Option C (ARP) is wrong because the Address Resolution Protocol maps a known IP address to a MAC address on a local network; it is used for layer 2 communication, not for IP address assignment. Option D (ICMP) is wrong because the Internet Control Message Protocol is used for error reporting and diagnostic functions (e.g., ping, traceroute); it has no role in dynamically assigning IP addresses.

83
MCQmedium

A network engineer is designing a network for a large organization. The engineer needs to ensure that broadcast traffic from one VLAN does not propagate to other VLANs while still allowing inter-VLAN communication. Which of the following devices is required to route between VLANs?

A.Layer 2 switch
B.Router
C.Bridge
D.Firewall
AnswerB

A router (or a Layer 3 switch acting as a router) can forward traffic between VLANs by performing routing at Layer 3.

Why this answer

A router is required to route between VLANs because VLANs segment a Layer 2 broadcast domain, and inter-VLAN communication must occur at Layer 3. The router performs routing by receiving frames tagged with the source VLAN, stripping the tag, making a forwarding decision based on the destination IP, and then re-encapsulating the frame with the destination VLAN tag. This process is often implemented using a router-on-a-stick configuration with 802.1Q trunking.

Exam trap

The trap here is that candidates often confuse a Layer 3 switch with a Layer 2 switch and assume any switch can route between VLANs, but a standard Layer 2 switch lacks the routing engine and IP forwarding table required for inter-VLAN communication.

How to eliminate wrong answers

Option A is wrong because a Layer 2 switch forwards frames based on MAC addresses within the same VLAN and cannot route between VLANs; it would require a Layer 3 switch or an external router to perform inter-VLAN routing. Option C is wrong because a bridge operates at Layer 2 to connect two network segments and does not perform IP routing; it would simply forward broadcast traffic between VLANs if they were on the same bridge domain, defeating the isolation requirement. Option D is wrong because a firewall is a security appliance that filters traffic based on rules and can route in some cases, but it is not the primary device designed for efficient inter-VLAN routing; using a firewall for this purpose would introduce unnecessary latency and complexity compared to a dedicated router or Layer 3 switch.

84
MCQeasy

A network administrator wants to logically segment a single physical switch into multiple separate broadcast domains without purchasing additional hardware. Which concept should be used?

A.Spanning Tree Protocol (STP)
B.Virtual LAN (VLAN)
C.Subnetting
D.Quality of Service (QoS)
AnswerB

VLANs segment a physical switch into multiple broadcast domains at Layer 2, requiring a router for inter-VLAN communication.

Why this answer

A VLAN logically segments a physical switch into multiple isolated broadcast domains by assigning switch ports to specific VLAN IDs (802.1Q). This prevents broadcast traffic from crossing VLAN boundaries without requiring additional hardware, as each VLAN functions as its own Layer 2 network.

Exam trap

Cisco often tests the misconception that subnetting alone can segment a switch, but subnetting is a Layer 3 concept and does not create separate broadcast domains on a single physical switch without VLANs.

How to eliminate wrong answers

Option A is wrong because STP prevents loops in a redundant switched network by blocking specific ports, but it does not create broadcast domains or segment traffic logically. Option C is wrong because subnetting is a Layer 3 technique used to divide IP address ranges into smaller networks, but it does not segment a single physical switch at Layer 2; VLANs are required for that. Option D is wrong because QoS prioritizes network traffic based on policies (e.g., DSCP or CoS values) but does not isolate broadcast domains or segment the switch.

85
MCQhard

A network engineer needs to connect two network segments that use different physical media: one segment uses copper Ethernet and the other uses fiber optic. The device must forward frames based on MAC addresses and must not perform any routing. Which device should the engineer choose?

A.Layer 3 switch
B.Media converter
C.Bridge
D.Router
AnswerC

A bridge operates at Layer 2, can connect different media types, and forwards frames using MAC addresses without routing.

Why this answer

A bridge operates at Layer 2, forwarding frames based on MAC addresses while connecting different physical media (e.g., copper to fiber). It does not perform routing, making it the correct choice for this scenario. Unlike a media converter, a bridge also provides segmentation and collision domain isolation.

Exam trap

CompTIA often tests the distinction between a media converter (Layer 1) and a bridge (Layer 2), leading candidates to choose the media converter because it handles physical media conversion, but they overlook the requirement for MAC address-based forwarding.

How to eliminate wrong answers

Option A is wrong because a Layer 3 switch performs routing at Layer 3 (IP forwarding), which is not required and violates the 'must not perform any routing' constraint. Option B is wrong because a media converter only translates physical layer signals (e.g., copper to fiber) without forwarding frames based on MAC addresses or providing Layer 2 segmentation. Option D is wrong because a router operates at Layer 3, forwarding packets based on IP addresses and performing routing, which is explicitly not allowed.

86
MCQeasy

A network switch is experiencing a high number of collisions on a specific port. The connected device is configured for half-duplex. Which of the following is the most likely cause?

A.The switch port is configured for full-duplex
B.The cable length exceeds 100 meters
C.The device is using an incorrect VLAN
D.The switch port is configured for 1000BASE-T but the device only supports 100BASE-TX
AnswerA

A duplex mismatch (switch full-duplex, device half-duplex) causes excessive collisions because the full-duplex switch transmits without checking for carrier sense, colliding with the half-duplex device's transmissions.

Why this answer

When a switch port is configured for full-duplex but the connected device operates in half-duplex, a duplex mismatch occurs. The switch transmits without checking for collisions (as full-duplex does not use CSMA/CD), while the half-duplex device expects to sense the carrier before sending, leading to collisions on the port. This is the most common cause of excessive collisions on a single switch port.

Exam trap

The trap here is that candidates often assume collisions are always caused by cable length or physical issues, overlooking the duplex mismatch as the primary cause when one side is half-duplex and the other is full-duplex.

How to eliminate wrong answers

Option B is wrong because cable length exceeding 100 meters typically causes attenuation and late collisions or CRC errors, not a high number of standard collisions on a half-duplex link. Option C is wrong because an incorrect VLAN assignment would cause connectivity issues or traffic isolation problems, not physical-layer collisions on the port.

87
MCQeasy

A network engineer needs to create subnets for four departments, each requiring at least 50 host addresses. The available network is 192.168.1.0/24. Which subnet mask should be used to satisfy the requirements while minimizing wasted addresses?

A./26 (255.255.255.192)
B./25 (255.255.255.128)
C./27 (255.255.255.224)
D./24 (255.255.255.0)
AnswerA

Correct. /26 provides 4 subnets with 62 usable hosts each, fitting the need for 50 hosts per department.

Why this answer

A /26 subnet mask (255.255.255.192) provides 62 usable host addresses per subnet (2^(32-26) - 2 = 62), which meets the requirement of at least 50 hosts per department. With a /24 network, you can create exactly four /26 subnets (192.168.1.0/26, 192.168.1.64/26, 192.168.1.128/26, 192.168.1.192/26), perfectly matching the four departments while minimizing wasted addresses.

Exam trap

The trap here is that candidates often choose /27 because they calculate 2^5 = 32 and forget to subtract 2 for the network and broadcast addresses, mistakenly thinking 32 hosts are available, or they choose /25 because they see it provides more than 50 hosts without realizing it only creates two subnets, not four.

How to eliminate wrong answers

Option B (/25, 255.255.255.128) is wrong because it provides 126 usable host addresses per subnet (2^7 - 2 = 126), which is far more than the required 50, and only yields two subnets from a /24 network, not enough for four departments. Option C (/27, 255.255.255.224) is wrong because it provides only 30 usable host addresses per subnet (2^5 - 2 = 30), which fails to meet the minimum requirement of 50 hosts per department.

88
MCQeasy

Which of the following IPv6 addresses is a valid link-local address?

A.fe80::1
B.2001:db8::1
C.ff02::1
D.10.0.0.1
AnswerA

fe80::/10 is the prefix for link-local addresses; fe80::1 is a common link-local address.

Why this answer

Option A is correct because link-local addresses in IPv6 always start with the prefix fe80::/10, and fe80::1 is a valid example. These addresses are automatically configured on interfaces for local link communication and are not routable beyond the local network segment.

Exam trap

Cisco often tests the distinction between link-local (fe80::/10) and unique local (fc00::/7) or global unicast (2000::/3) addresses, and candidates frequently confuse the fe80 prefix with multicast or documentation ranges.

How to eliminate wrong answers

Option B is wrong because 2001:db8::1 is a documentation prefix (2001:db8::/32) used for examples in RFC 3849, not a link-local address. Option C is wrong because ff02::1 is the all-nodes multicast address (prefix ff00::/8), not a unicast link-local address. Option D is wrong because 10.0.0.1 is an IPv4 private address (RFC 1918), not an IPv6 address at all.

89
MCQmedium

A network technician is explaining the difference between TCP and UDP to a junior technician. Which of the following correctly identifies a characteristic of TCP but NOT of UDP?

A.It provides connectionless communication with minimal overhead.
B.It supports multicast and broadcast transmissions.
C.It uses a three-way handshake to establish a connection before data transfer.
D.It is commonly used for real-time applications like VoIP and video streaming.
AnswerC

TCP uses a three-way handshake (SYN, SYN-ACK, ACK) to establish a reliable connection. UDP does not have a handshake; it sends data immediately.

Why this answer

TCP is a connection-oriented protocol that uses a three-way handshake (SYN, SYN-ACK, ACK) to establish a reliable connection before any data is transmitted, ensuring ordered delivery and error recovery. UDP, in contrast, is connectionless and sends datagrams without any prior setup, making the three-way handshake a defining characteristic of TCP only.

Exam trap

The trap here is that candidates often confuse the three-way handshake with general connection establishment, forgetting that UDP is stateless and never performs any handshake, while TCP always does before data transfer.

How to eliminate wrong answers

Option A is wrong because connectionless communication with minimal overhead is a characteristic of UDP, not TCP; TCP is connection-oriented and adds overhead for reliability. Option B is wrong because multicast and broadcast transmissions are supported by UDP, while TCP is unicast-only and cannot deliver to multiple destinations simultaneously. Option D is wrong because real-time applications like VoIP and video streaming typically use UDP due to its low latency and tolerance for packet loss, not TCP which would introduce retransmission delays.

90
MCQeasy

A network switch forwards frames based on which address?

A.MAC address
B.IP address
C.Port number
D.Domain name
AnswerA

Correct. Switches use MAC addresses to forward frames within the same local network.

Why this answer

A network switch operates at Layer 2 (Data Link Layer) of the OSI model and uses MAC addresses to make forwarding decisions. When a frame arrives, the switch examines the destination MAC address, looks it up in its MAC address table (CAM table), and forwards the frame only to the port associated with that MAC address, reducing collision domains and improving network efficiency.

Exam trap

CompTIA often tests the distinction between Layer 2 switching (MAC addresses) and Layer 3 routing (IP addresses), and the trap here is that candidates mistakenly associate 'forwarding' with IP addresses because they think of routers, forgetting that the question specifically asks about a switch.

How to eliminate wrong answers

Option B (IP address) is wrong because IP addresses are used by routers (Layer 3 devices) for packet forwarding, not by switches; switches do not examine IP headers unless they are multilayer switches with routing enabled. Option C (Port number) is wrong because port numbers are used by transport layer protocols (TCP/UDP) to identify specific applications or services, and switches do not inspect Layer 4 headers. Option D (Domain name) is wrong because domain names are resolved to IP addresses by DNS (Application Layer) and are never used by switches for frame forwarding.

91
MCQeasy

A network switch that forwards frames based on MAC addresses operates at which layer of the OSI model?

A.Physical
B.Data Link
C.Network
D.Transport
AnswerB

Switches make forwarding decisions based on MAC addresses, which is a Layer 2 function.

Why this answer

A network switch that forwards frames based on MAC addresses operates at Layer 2, the Data Link layer. This layer is responsible for node-to-node data transfer and error detection using MAC addresses, as defined by IEEE 802 standards. Switches build a MAC address table by learning source MAC addresses from incoming frames and use this table to make forwarding decisions.

Exam trap

Cisco often tests the misconception that switches operate at Layer 3 because they can be configured with IP addresses for management (e.g., SVI), but the core frame-forwarding function remains at Layer 2 using MAC addresses.

How to eliminate wrong answers

Option A is wrong because the Physical layer (Layer 1) deals with raw bit transmission over physical media, such as electrical signals, light pulses, or radio waves, and does not interpret MAC addresses or frames. Option C is wrong because the Network layer (Layer 3) uses logical addressing (e.g., IP addresses) for routing packets between networks, not MAC addresses for frame forwarding within a local network.

92
Matchingmedium

Match each network protocol to its well-known port number.

Drag a concept onto its matching description — or click a concept then click the description.

Concepts
Matches

22

443

53

25

3389

Why these pairings

These are standard well-known port assignments.

93
MCQmedium

A network administrator is designing a small office network with 40 workstations. The design must ensure that a single cable failure only affects the connected workstation. Which logical topology should the administrator implement?

A.Star
B.Ring
C.Bus
D.Mesh
AnswerA

In a star topology, each device has a dedicated cable to a central switch, so a cable failure only affects that single device.

Why this answer

A star topology connects each workstation directly to a central switch or hub, so a cable failure only affects the single connected workstation, not the rest of the network. This meets the requirement for fault isolation at the workstation level, which is the core design goal in a small office with 40 devices.

Exam trap

CompTIA often tests the distinction between physical and logical topology—candidates may confuse a physical star with a logical bus (e.g., early Ethernet using a hub) and incorrectly assume a cable failure only affects one workstation, but a hub-based star is logically a bus where a collision domain spans all ports, though the physical cable break still isolates only the connected device.

How to eliminate wrong answers

Option B (Ring) is wrong because in a ring topology, each workstation is connected to two neighbors, and a single cable break can disrupt the entire ring unless a dual-ring or self-healing protocol (e.g., FDDI or RPR) is used, which still affects multiple workstations. Option C (Bus) is wrong because a bus topology uses a single shared backbone cable; a break anywhere on the backbone can partition the network and affect all workstations on that segment. Option D (Mesh) is wrong because while a full mesh provides redundancy, a partial mesh still requires multiple connections per workstation, and a single cable failure only affects the directly connected workstation only if the topology is star-based; mesh is typically used for high-availability backbones, not for isolating workstation failures.

94
MCQeasy

Which of the following is the primary function of a subnet mask in IPv4 networking?

A.It identifies the default gateway for a subnet
B.It determines the network portion of an IP address
C.It provides encryption for data in transit
D.It maps IP addresses to MAC addresses
AnswerB

By applying the subnet mask (AND operation) to the IP address, the network address is extracted. This is the core purpose of the subnet mask.

Why this answer

The subnet mask's primary function is to distinguish the network portion from the host portion of an IPv4 address. By applying a bitwise AND operation between the IP address and the subnet mask, the network address is derived, which is essential for routing decisions. Without this separation, devices cannot determine whether a destination is local or requires forwarding through a router.

Exam trap

The trap here is that candidates often confuse the subnet mask's role with that of the default gateway, mistakenly thinking the mask itself identifies the router address, when in fact the mask only defines the network/host boundary and has no direct relationship to gateway configuration.

How to eliminate wrong answers

Option A is wrong because the default gateway is identified by a separate configuration parameter (e.g., via DHCP or static assignment), not by the subnet mask; the subnet mask only defines the network boundary. Option C is wrong because encryption for data in transit is provided by protocols such as IPsec, TLS, or SSH, not by the subnet mask, which is a purely logical addressing mechanism with no cryptographic function.

95
MCQeasy

Which of the following network protocols operates at the Transport layer of the OSI model and provides connection-oriented, reliable data delivery?

A.UDP
B.TCP
C.IP
D.ARP
AnswerB

TCP provides connection-oriented, reliable data delivery with features like flow control, error checking, and retransmission of lost packets.

Why this answer

TCP (Transmission Control Protocol) operates at the Transport layer (Layer 4) of the OSI model and provides connection-oriented, reliable data delivery through mechanisms such as three-way handshake, sequence numbers, acknowledgments, and retransmission of lost segments. This ensures that data is delivered in order and without errors, making TCP the correct choice for the question.

Exam trap

The trap here is that candidates often confuse IP (Network layer) with a transport protocol or mistakenly think UDP provides reliability because it has checksums, but UDP lacks connection setup and retransmission, making TCP the only correct answer for connection-oriented reliable delivery.

How to eliminate wrong answers

Option A (UDP) is wrong because it is a connectionless Transport layer protocol that provides unreliable, best-effort delivery without acknowledgments or retransmissions, making it unsuitable for connection-oriented reliable data delivery. Option C (IP) is wrong because it operates at the Network layer (Layer 3) and is responsible for addressing and routing packets, not for providing transport-layer reliability or connection-oriented service.

96
MCQeasy

Which of the following best describes a broadcast domain?

A.All devices connected to the same switch
B.All devices that share the same IP subnet
C.All devices that can receive a broadcast frame from any other device in the network segment
D.All devices that have the same MAC address prefix
AnswerC

This is the precise definition. A broadcast domain consists of all devices that will receive a broadcast frame sent by any device within the same logical boundary.

Why this answer

A broadcast domain is defined as the set of all devices that can receive a broadcast frame (destination MAC FF:FF:FF:FF:FF:FF) sent by any other device within the same network segment. This boundary is typically enforced by Layer 3 devices like routers, which do not forward broadcast frames, whereas Layer 2 switches forward broadcasts out all ports except the receiving port within the same VLAN.

Exam trap

The trap here is that candidates often confuse a broadcast domain with a collision domain or assume all devices on the same switch are in the same broadcast domain, ignoring VLAN segmentation.

How to eliminate wrong answers

Option A is wrong because a single switch can be divided into multiple VLANs, each forming its own broadcast domain; devices on different VLANs on the same switch cannot receive each other's broadcasts. Option B is wrong because multiple IP subnets can exist within the same broadcast domain (e.g., using proxy ARP or unnumbered interfaces), and conversely, a single IP subnet can span multiple broadcast domains if routers are used to segment them. Option D is wrong because MAC address prefixes (OUI) identify the manufacturer, not broadcast domain membership; devices with different OUIs can be in the same broadcast domain, and devices with the same OUI can be in different broadcast domains.

97
MCQeasy

A network administrator needs to create a subnet that supports exactly 50 hosts. Which subnet mask provides the smallest subnet that meets this requirement?

A.A
B.B
C.C
D.D
AnswerB

/26 provides 62 usable addresses, which is the minimum that supports 50 hosts.

Why this answer

Option B is correct because a /26 subnet mask (255.255.255.192) provides 62 usable host addresses (2^(32-26) - 2 = 64 - 2 = 62), which is the smallest subnet that supports at least 50 hosts. A /27 would only provide 30 usable addresses, which is insufficient.

Exam trap

The trap here is that candidates often forget to subtract 2 for the network and broadcast addresses, leading them to choose a /27 (which has 32 total addresses but only 30 usable) thinking it supports 50 hosts.

How to eliminate wrong answers

Option A is wrong because it represents a /27 subnet mask (255.255.255.224), which provides only 30 usable hosts (2^5 - 2 = 30), insufficient for 50 hosts. Option C is wrong because it represents a /25 subnet mask (255.255.255.128), which provides 126 usable hosts (2^7 - 2 = 126), far more than needed and not the smallest subnet that meets the requirement. Option D is wrong because it represents a /24 subnet mask (255.255.255.0), which provides 254 usable hosts (2^8 - 2 = 254), excessively large and not the smallest option.

98
MCQeasy

Which of the following best describes the function of a default gateway on a host?

A.It forwards packets destined for networks other than the local subnet
B.It resolves domain names to IP addresses
C.It assigns IP addresses to devices on the local network
D.It filters traffic based on MAC addresses
AnswerA

Correct. The default gateway provides a route to remote networks.

Why this answer

The default gateway is the router interface on the local subnet that a host uses to send packets destined for IP addresses outside its own subnet. When a host determines that the destination IP is not reachable via ARP on the local link, it forwards the packet to the default gateway's MAC address, which then routes the packet toward the remote network. This is essential for inter-subnet communication in any IP network.

Exam trap

The trap here is that candidates often confuse the default gateway with a DNS server or DHCP server, because in many home networks the same device (the router) performs all three roles, but the exam tests the distinct Layer 3 routing function of the default gateway in isolation.

How to eliminate wrong answers

Option B is wrong because domain name resolution is performed by a DNS server, not the default gateway; the default gateway operates at Layer 3 (IP routing) and has no role in DNS lookups. Option C is wrong because IP address assignment on a local network is typically handled by a DHCP server, which may or may not be the same device as the default gateway, but the function of assigning addresses is not a property of the default gateway itself. Option D is wrong because filtering traffic based on MAC addresses is a Layer 2 function performed by switches or firewall rules, not by the default gateway, which forwards packets based on IP destination addresses.

99
MCQeasy

A network administrator needs to connect 10 workstations in a way that each workstation's traffic does not collide with others. Which device should be used to connect these workstations?

A.Hub
B.Switch
C.Router
D.Modem
AnswerB

Correct. Each port on a switch is a separate collision domain, preventing collisions between different workstations.

Why this answer

A switch is the correct device because it operates at Layer 2 of the OSI model, using MAC addresses to forward frames only to the specific destination port. This creates separate collision domains for each connected workstation, ensuring that traffic from one workstation does not collide with traffic from another.

Exam trap

The trap here is that candidates often confuse a hub with a switch, thinking both simply 'connect' devices, but the key differentiator is that a hub creates a single collision domain while a switch creates separate collision domains per port.

How to eliminate wrong answers

Option A is wrong because a hub operates at Layer 1 and simply repeats electrical signals out all ports, forcing all workstations to share a single collision domain — any two devices transmitting simultaneously will cause a collision. Option C is wrong because a router operates at Layer 3 and is designed to forward packets between different IP subnets, not to provide collision-free connectivity within a single broadcast domain; using a router here would be overkill and would not address the Layer 2 collision issue.

100
MCQeasy

At which OSI layer does a router primarily operate to make forwarding decisions based on IP addresses?

A.Layer 1 (Physical)
B.Layer 2 (Data Link)
C.Layer 3 (Network)
D.Layer 4 (Transport)
AnswerC

The Network layer handles logical addressing (IP) and routing decisions.

Why this answer

A router primarily operates at Layer 3 (Network) of the OSI model because it uses logical IP addresses (e.g., IPv4 or IPv6) to make forwarding decisions. The router examines the destination IP address in the packet header, performs a longest-prefix match against its routing table, and determines the next-hop interface. This layer is responsible for end-to-end delivery and path selection across multiple networks.

Exam trap

CompTIA often tests the misconception that routers operate at Layer 2 because they forward frames, but the key distinction is that routers make forwarding decisions based on Layer 3 IP addresses, not Layer 2 MAC addresses.

How to eliminate wrong answers

Option A is wrong because Layer 1 (Physical) deals with raw bit transmission over physical media (e.g., cables, signals) and does not interpret IP addresses or make forwarding decisions. Option B is wrong because Layer 2 (Data Link) uses MAC addresses for forwarding within a single broadcast domain (e.g., switches) and cannot route between different IP subnets. Option D is wrong because Layer 4 (Transport) handles end-to-end communication, segmentation, and port numbers (e.g., TCP/UDP), not IP-based routing decisions.

101
MCQeasy

Which of the following devices operates at Layer 3 of the OSI model and makes forwarding decisions based on destination IP addresses?

A.Switch
B.Bridge
C.Router
D.Hub
AnswerC

A router routes packets based on Layer 3 IP addresses and maintains a routing table.

Why this answer

A router operates at Layer 3 (Network layer) of the OSI model and uses the destination IP address in the packet header to make forwarding decisions. It maintains a routing table (e.g., via OSPF, EIGRP, or static routes) to determine the next-hop interface for each packet, enabling communication between different subnets or VLANs.

Exam trap

The trap here is that candidates often confuse a Layer 3 switch with a router, but the question specifies a device that makes forwarding decisions based on destination IP addresses, which is the defining function of a router, not a switch (even a multilayer switch still uses MAC addresses for most forwarding unless explicitly configured for routing).

How to eliminate wrong answers

Option A is wrong because a switch operates primarily at Layer 2 (Data Link layer) and forwards frames based on destination MAC addresses, not IP addresses. Option B is wrong because a bridge also operates at Layer 2, connecting two network segments and forwarding frames using MAC addresses, not IP addresses. Option D is wrong because a hub operates at Layer 1 (Physical layer) and simply repeats electrical signals out all ports without any intelligence to make forwarding decisions based on IP or MAC addresses.

102
MCQeasy

Which protocol is used to resolve a known IP address to a corresponding MAC address on a local network?

A.ARP
B.DNS
C.DHCP
D.ICMP
AnswerA

ARP (Address Resolution Protocol) maps IPv4 addresses to MAC addresses. It is essential for local network communication.

Why this answer

ARP (Address Resolution Protocol) is used to resolve a known IP address to its corresponding MAC address on a local network. When a host needs to send a frame to another host on the same subnet, it broadcasts an ARP request containing the target IP; the host with that IP responds with its MAC address, which is then cached for future use.

Exam trap

The trap here is confusing ARP with DNS, as both involve 'resolution,' but DNS resolves names to IPs (Layer 3) while ARP resolves IPs to MACs (Layer 2), and candidates often forget ARP operates only within a local broadcast domain.

How to eliminate wrong answers

Option B (DNS) is wrong because DNS resolves domain names to IP addresses, not IP addresses to MAC addresses. Option C (DHCP) is wrong because DHCP assigns IP addresses dynamically and provides configuration parameters like subnet mask and default gateway, but does not perform MAC-to-IP resolution. Option D (ICMP) is wrong because ICMP is used for error reporting and diagnostic functions (e.g., ping, traceroute), not for address resolution.

103
MCQeasy

Which of the following best describes the primary function of the transport layer in the OSI model?

A.Routing packets across networks
B.Providing end-to-end communication and data flow control
C.Encoding data into electrical signals
D.Determining the best path for data transmission
AnswerB

This is correct. The transport layer (Layer 4) manages end-to-end connections, segmenting data, controlling flow, and ensuring reliable delivery.

Why this answer

The transport layer (Layer 4) is responsible for end-to-end communication between hosts, including segmentation, reassembly, and flow control. Protocols like TCP use windowing and acknowledgments to manage data flow, ensuring reliable delivery. This distinguishes it from lower layers that handle routing or physical signaling.

Exam trap

CompTIA often tests the confusion between the transport layer's end-to-end delivery and the network layer's path determination, leading candidates to incorrectly select routing-related options like A or D.

How to eliminate wrong answers

Option A is wrong because routing packets across networks is a function of the network layer (Layer 3), handled by protocols like IP and routing protocols such as OSPF or BGP. Option C is wrong because encoding data into electrical signals is the role of the physical layer (Layer 1), which deals with bit transmission over media like copper or fiber. Option D is wrong because determining the best path for data transmission is also a network layer function, performed by routers using routing tables and metrics like hop count or cost.

104
MCQeasy

A network administrator is troubleshooting a connectivity issue and suspects the problem is related to the physical cabling. At which layer of the OSI model should the administrator begin their investigation?

A.Transport layer
B.Data Link layer
C.Physical layer
D.Network layer
AnswerC

The Physical layer defines the electrical, mechanical, and procedural interface to the transmission medium, making it the correct layer for cabling issues.

Why this answer

The Physical layer (Layer 1) is the correct starting point because the administrator suspects the problem is related to physical cabling. The Physical layer defines the electrical, mechanical, and procedural specifications for transmitting raw bits over a physical medium, such as copper or fiber optic cables. Troubleshooting at this layer involves checking for cable faults, signal degradation, or improper termination before moving up the OSI stack.

Exam trap

The trap here is that candidates often jump to the Data Link layer (Layer 2) because they associate 'connectivity issues' with MAC addresses or switching, forgetting that physical cabling faults must be ruled out first at Layer 1.

How to eliminate wrong answers

Option A is wrong because the Transport layer (Layer 4) handles end-to-end communication, segmentation, and flow control (e.g., TCP/UDP), not physical cabling issues. Option B is wrong because the Data Link layer (Layer 2) manages framing, MAC addressing, and error detection (e.g., Ethernet frames, switches), but it assumes the physical medium is functioning correctly; cabling faults are a Layer 1 concern.

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