CCNA Network Infrastructure and Connectivity Practice Test 3 — 15 Questions

Question 1

Drag and drop the wireless LAN terms on the left to their correct descriptions on the right.

Accepted Answer

SSID: The network name broadcast by a wireless access point.. The SSID is the network name broadcast by an AP, so it matches that description. The BSSID is the MAC address of the AP's radio interface, making that pairing correct. WPA2 is a security protocol that uses AES encryption for Wi-Fi, so it correctly matches its description. The beacon frame is a management frame broadcast periodically to announce the presence of a WLAN, which aligns with that description.

Question 2

Drag and drop the wireless LAN terms on the left to the correct descriptions on the right.

Accepted Answer

Access Point (AP). The question stem lacks the descriptions to match. Without them, marking AP as correct is unverifiable. Also, the explanation covers extra terms, which is inconsistent with a matching question.

Answer

Service Set Identifier (SSID)

Answer

Basic Service Set (BSS)

Answer

Wireless LAN Controller (WLC)

Question 3

A network engineer notices that a critical link between two Cisco Catalyst 9300 switches is flapping every few minutes. The link uses a 10GBASE-SR SFP+ module on one end and a 10GBASE-LR SFP+ module on the other. The interface logs show 'Link error recovery - will restart'. The distance between the switches is 500 meters. Which command output best confirms the root cause of the flapping?

Accepted Answer

show interfaces transceiver. The 'show interfaces transceiver' command displays the type, serial number, and optical parameters of the SFP+ modules. In this scenario, one end uses 10GBASE-SR (multimode, 850nm) and the other uses 10GBASE-LR (single-mode, 1310nm). These transceivers are not interoperable because they operate on different wavelengths and require different fiber types. The interface repeatedly attempts link recovery and flaps as a result. The distance of 500 meters is not the root cause; even a short link would fail with this mismatched pair. The transceiver command confirms the mismatch by showing the transceiver types on both ends.

Answer

show interfaces status

Answer

show interfaces gigabitethernet1/0/1

Answer

show logging

Question 4

Which TWO of the following are correct regarding Cisco SFP/SFP+ transceivers and their supported cable types?

Accepted Answer

A 1000BASE-T SFP transceiver can operate over Category 5e UTP cable up to 100 meters.. Correct answers are B and C. A 1000BASE-T SFP transceiver operates over Cat 5e or better UTP up to 100 meters as defined by IEEE 802.3ab, making B true. A 10GBASE-LR SFP+ transceiver supports up to 10 km over single-mode fiber, making C true. Option A is false because standard SFP+ fiber transceivers are not designed for UTP cabling; they require fiber or direct-attach copper cables. Option D is false because 1000BASE-SX has a maximum distance of 550 meters over multimode fiber, not 5 km. Option E is false because SFP+ modules are not backward compatible with SFP slots; SFP slots are designed for 1 Gbps SFP modules only. Backward compatibility works the other way: SFP modules can be used in SFP+ slots.

Answer

A standard SFP+ fiber transceiver can be used with Category 6a UTP cable to achieve 10 Gbps over 100 meters.

Answer

An SFP transceiver for 1000BASE-SX can achieve distances up to 5 kilometers over multimode fiber.

Answer

SFP+ transceivers are backward compatible with SFP slots and can operate at 1 Gbps if the module supports it.

Question 5

Drag and drop the cable or transceiver types on the left to the corresponding distance limits or characteristics on the right.

Accepted Answer

1000BASE-T: 100 meters. 1000BASE-T over Cat5e/6 UTP copper has a maximum distance of 100 meters. 1000BASE-SX over 50/125 µm multimode fiber supports up to 550 meters (220/275 m on 62.5/125 µm, but 550 m is the commonly quoted maximum for 50/125 µm). 1000BASE-LX over single-mode fiber supports up to 5 kilometers (550 m on multimode with mode-conditioning patch cord). 1000BASE-ZX is a Cisco-defined single-mode transceiver supporting distances up to 70 kilometers. Therefore, each listed pairing is correct.

Question 6

Drag and drop the layer names on the left to the correct PDU names on the right.

Accepted Answer

Application Layer: PDU - Data. Each OSI layer uses a specific PDU name: Application uses Data (option A correct), Transport uses Segment (option B correct), Network uses Packet (option C correct), Data Link uses Frame (option D correct).

Question 7

Drag and drop the OSI layer names on the left to the correct PDU names on the right.

Accepted Answer

Physical layer: Bits. Each OSI layer has a specific PDU: Physical layer transmits bits, Data Link layer formats data into frames, Network layer handles packets, and Transport layer manages segments. All four options correctly match the layer to its PDU.

Question 8

Drag and drop the OSI model layer names on the left to the correct PDU name and responsibility description on the right.

Accepted Answer

Layer 2: Data Link - PDU: Frame - Responsibility: Provides node-to-node data transfer and handles error detection from the Physical layer.. In this matching exercise, only Option A correctly pairs Layer 2 (Data Link) with the PDU Frame and the responsibility 'Provides node-to-node data transfer and handles error detection from the Physical layer.' Options B, C, and D are incorrect matches. Option B pairs Layer 3 (Network) with Packet, which is correct for the PDU, but the responsibility 'Provides end-to-end delivery and logical addressing' is inaccurate because end-to-end delivery is a function of the Transport layer, not the Network layer. The Network layer focuses on routing and logical addressing, not end-to-end delivery. Option C pairs Layer 4 (Transport) with Segment, which is correct for the PDU, but the responsibility incorrectly includes 'error recovery', which is not a generic Transport layer function; it is specific to TCP and not UDP. Moreover, the description 'between hosts' is vague and does not clearly distinguish Transport from Network. Option D pairs Layer 1 (Physical) with Bits, but the responsibility 'Transmits raw bit stream over the physical medium' is too broad and does not capture the Physical layer's role in encoding, signaling, and media specifics. Additionally, the term 'raw bit stream' is ambiguous; the Physical layer deals with electrical or optical signals representing bits, not raw bits themselves. Therefore, only Option A is correctly matched.

Answer

Layer 3: Network - PDU: Packet - Responsibility: Provides end-to-end delivery and logical addressing (IP addresses) for routing across networks.

Answer

Layer 4: Transport - PDU: Segment - Responsibility: Provides reliable or unreliable delivery and error recovery between hosts.

Answer

Layer 1: Physical - PDU: Bits - Responsibility: Transmits raw bit stream over the physical medium.

Question 9

Drag and drop the interface error types on the left to the corresponding descriptions on the right.

Accepted Answer

CRC errors. CRC errors correspond to frames with an invalid checksum, which is the correct match. Runts are frames smaller than 64 bytes, not related to checksum errors. Giants are frames larger than the maximum size, also not related to CRC. Late collisions occur after the first 64 bytes of transmission and are timing issues, not checksum failures. Therefore, only CRC errors (option A) is correct.

Answer

Runts

Answer

Giants

Answer

Late collisions

Question 10

Drag and drop the cable issue symptoms on the left to the correct descriptions on the right.

Accepted Answer

Crosstalk: Interference caused by electromagnetic coupling between adjacent cables.. Crosstalk is the interference caused by electromagnetic coupling between adjacent cables, where signals from one cable induce currents in another. Attenuation is the loss of signal strength over distance due to resistance and leakage. Impedance mismatch occurs when the cable's characteristic impedance changes, causing signal reflections. Split pair refers to incorrect wire pairing that breaks the twisted-pair design, leading to excessive crosstalk. This question tests the ability to match each symptom to its correct definition.

Answer

Attenuation: Loss of signal strength over the length of the cable.

Answer

Impedance mismatch: Reflection of signals due to inconsistent cable impedance.

Answer

Split pair: Incorrect wire pairing causing excessive crosstalk.

Question 11

A network engineer is troubleshooting a workstation that cannot access the internet. The workstation is connected to a switch port configured for access VLAN 10. The switch is a Cisco 2960-X running Cisco IOS. The engineer runs 'ipconfig /all' on the workstation and sees an IPv4 address of 169.254.123.45 with a subnet mask of 255.255.0.0. The engineer then connects to the switch and issues 'show interfaces vlan 10'. What is the most likely cause of the issue?

Accepted Answer

The switch's VLAN 10 SVI is administratively down.. The workstation has an APIPA address (169.254.x.x), which indicates it failed to obtain a DHCP lease. Since the switch's VLAN 10 SVI is administratively down, the workstation cannot reach the DHCP server (which may be on a different subnet or the SVI itself), causing the DHCP request to time out and the workstation to self-assign an APIPA address. Option B is correct because an administratively down SVI breaks Layer 3 connectivity for that VLAN, preventing DHCP traffic from being routed.

Answer

The workstation is not configured to use DHCP.

Answer

The switch port connecting the workstation is in a different VLAN.

Answer

The DHCP server is not configured on the network.

Question 12

Drag and drop the wireless terms on the left to the correct descriptions on the right.

Accepted Answer

SSID: The network name broadcast by the access point to identify the wireless network.. SSID, BSSID, and Beacon are correctly matched. However, Channel is incorrectly described as '2.4 GHz or 5 GHz bands' — these are frequency bands, not channels. A channel is a specific subdivision within a band, such as 2.4 GHz channel 6. Therefore, option C is not a correct pairing.

Answer

Channel: A specific frequency range used for wireless communication, such as 2.4 GHz or 5 GHz bands.

Question 13

Drag and drop the Wi-Fi features on the left to the correct descriptions on the right.

Accepted Answer

MIMO: Uses multiple antennas to improve throughput and range. 802.11ax (Wi-Fi 6) uses OFDMA to divide channels into smaller subcarriers, allowing simultaneous transmission to multiple clients and improving efficiency in dense environments. WPA3-Personal employs Simultaneous Authentication of Equals (SAE) to replace the vulnerable pre-shared key handshake, providing secure password-based authentication resistant to offline dictionary attacks. A Basic Service Set (BSS) is the fundamental building block of a WLAN, consisting of a single access point (AP) and all associated wireless clients. A Wireless LAN Controller (WLC) centralizes AP management, handling configuration, firmware updates, and seamless roaming across multiple APs. Channel bonding (80 MHz) combines two 40 MHz channels, doubling the channel width to increase throughput; it is commonly used in 802.11ac (Wi-Fi 5) to achieve higher data rates.

Question 14

A user reports intermittent connectivity to the corporate web server at 10.1.1.100. The user's PC (IP 192.168.1.50/24, gateway 192.168.1.1) can ping the gateway and other local hosts, but pings to the web server time out every few seconds. The network administrator runs a traceroute from the PC and checks the local ARP cache. What is the most likely cause of the intermittent connectivity?

Accepted Answer

The web server at 10.1.1.100 has a duplicate IP address conflict with another device on the same subnet.. The intermittent connectivity (pings time out every few seconds) suggests an issue on the destination subnet rather than the source. The user can successfully ping the gateway and other local hosts, so the PC's configuration and the local network are functional. A duplicate IP address conflict on the web server's subnet causes the switch's MAC address table to toggle between two MAC addresses for 10.1.1.100, resulting in packets reaching the correct server only intermittently. This behavior explains the periodic failures seen in the pings.

Answer

The default gateway 192.168.1.1 is not configured to route traffic to the 10.1.1.0/24 network.

Answer

The user's PC has an incorrect subnet mask configured, preventing communication with the web server.

Answer

The web server is powered off or has a faulty network interface card.

Question 15

Drag and drop the following steps into the correct order to replace a faulty SFP module on a Cisco switch and verify the fiber interface.

Accepted Answer

Remove the faulty SFP module from the switch port.. The correct sequence is: remove the faulty SFP module (A), install the new SFP module (C), connect the fiber cable (B), and finally verify using 'show interfaces' and 'show interfaces transceiver' commands (D). This order ensures proper handling and avoids damage.