CCNA Network Infrastructure and Connectivity Practice Test 15 — 15 Questions

Question 1

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

Accepted Answer

SSID: The network name broadcast by an access point to identify the wireless network.. 802.11ac (Wi-Fi 5) operates only in the 5 GHz band and introduced support for 160 MHz-wide channels to achieve higher throughput. 802.11ax (Wi-Fi 6) adds OFDMA for more efficient channel use and works in both 2.4 GHz and 5 GHz bands. WPA3-Personal uses SAE (Simultaneous Authentication of Equals) to protect pre-shared key authentication against offline dictionary attacks. A Basic Service Set (BSS) consists of a single AP and its associated clients, identified by the AP's radio MAC address (BSSID). A Wireless LAN Controller (WLC) centralizes management, handling AP configuration, client roaming, and security policies across the wireless network.

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BSSID: The MAC address of the access point's radio interface, used to uniquely identify a BSS.

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RSSI: A measurement of the power level of the received radio signal, indicating signal strength.

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DFS: A mechanism that allows wireless devices to avoid interference with radar systems by dynamically selecting channels.

Question 2

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.. 802.11ac (Wi-Fi 5) uses OFDM and can bond channels up to 160 MHz, but operates exclusively in the 5 GHz band. 802.11ax (Wi-Fi 6) uses OFDMA for more efficient multi-user access and works in both 2.4 GHz and 5 GHz. WPA3-Personal secures pre-shared keys with SAE, replacing WPA2’s PSK, while WPA3-Enterprise uses 192-bit encryption and EAP for strong authentication. An autonomous AP functions standalone without a wireless controller.

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BSSID: The MAC address of the access point's radio interface, used to uniquely identify the access point.

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

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Beacon: A management frame sent periodically by the access point to announce the presence of the wireless network.

Question 3

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 4

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 and successful pings to the gateway and local hosts, combined with a traceroute that likely shows the first hop succeeding but subsequent hops failing, point to a duplicate IP address conflict on the web server's subnet. When two devices share the same IP address (10.1.1.100), the switch's MAC address table flips between the two MAC addresses, causing packets to reach the correct server only intermittently. This explains why pings time out every few seconds rather than failing consistently.

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

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

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

Question 5

A network technician is troubleshooting a connectivity issue for a PC connected to switch port Gi1/0/12. The PC can ping its default gateway (192.168.10.1) but cannot ping a server at 192.168.20.10. The switch is configured with VLAN 10 for the access port and is connected to a router-on-a-stick. The technician runs 'show vlan brief' and 'show interfaces trunk' on the switch. What is the most likely cause of the problem?

Accepted Answer

The router is missing a subinterface for VLAN 20.. The PC can ping its default gateway (192.168.10.1) but not the server at 192.168.20.10, indicating Layer 3 routing is failing between VLANs. Since the switch is configured with VLAN 10 for the access port and uses a router-on-a-stick, the router must have a subinterface for VLAN 20 to route traffic to the server's subnet. The absence of a subinterface for VLAN 20 prevents the router from forwarding packets from VLAN 10 to VLAN 20, making option B correct.

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The trunk port Gi1/0/24 is not in trunking mode.

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The switch port Gi1/0/12 is not assigned to VLAN 10.

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The PC has a duplicate IP address with the server.

Question 6

Which TWO commands would a network administrator use to verify that a client has received a valid IP address from a DHCP server and can resolve domain names to IP addresses?

Accepted Answer

ipconfig /all. Option A (ipconfig /all) is correct because it displays the full TCP/IP configuration for all network adapters, including whether DHCP is enabled, the assigned IP address, subnet mask, default gateway, and the DHCP server address. This allows the administrator to confirm that the client received a valid IP address from the DHCP server. Option D (nslookup www.courseiva.com) is correct because it queries the configured DNS server to resolve the domain name to an IP address, verifying that name resolution is working. Option B (ping 127.0.0.1) only tests the local TCP/IP stack and does not verify DHCP assignment or DNS resolution. Option C (tracert 8.8.8.8) uses an IP address directly and does not test domain-name resolution. Option E (arp -a) displays the ARP cache, which is unrelated to DHCP or DNS.

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ping 127.0.0.1

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tracert 8.8.8.8

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arp -a

Question 7

Which TWO commands would a network engineer use to verify that a Windows client has received an IP address from a DHCP server and can resolve a domain name to an IP address?

Accepted Answer

ipconfig /all. Option B is correct because `ipconfig /all` displays the full TCP/IP configuration for all adapters, including whether the IP address was obtained from a DHCP server (the DHCP Enabled and DHCP Server fields). Option D is correct because `nslookup www.courseiva.com` queries the configured DNS server to resolve the domain name to an IP address, confirming DNS resolution works.

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ping 8.8.8.8

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tracert www.courseiva.com

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arp -a

Question 8

Which TWO commands or tools would a network engineer use to verify if a client has a duplicate IP address conflict on the local subnet?

Accepted Answer

arp -a. The `arp -a` command displays the local ARP cache, which maps IP addresses to MAC addresses. If a duplicate IP exists on the subnet, the ARP cache may show inconsistent or rapidly changing MAC-to-IP mappings, and the local host may receive duplicate address detection messages, indicating a conflict. Other commands like `ipconfig`, `ping`, `nslookup`, and `tracert` do not directly reveal ARP-level conflicts.

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ipconfig /all

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nslookup

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ping

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tracert

Question 9

A network administrator is troubleshooting a user's wired workstation that cannot access the internet. The user reports that the workstation was working earlier today. The administrator runs 'ipconfig /all' on the workstation and sees an IP address of 169.254.10.55. What is the most likely cause of this issue?

Accepted Answer

The workstation is unable to communicate with a DHCP server due to a faulty network cable.. The IP address 169.254.10.55 falls within the Automatic Private IP Addressing (APIPA) range (169.254.0.0/16, RFC 3927). This address is assigned by the operating system when a DHCP client fails to receive a response from a DHCP server. A faulty network cable would prevent the workstation from communicating with the DHCP server, causing the client to self-assign an APIPA address after the DHCP discovery process times out.

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The workstation has a duplicate IP address conflict with another device.

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The workstation's DNS server settings are misconfigured.

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The workstation is connected to the wrong VLAN, causing it to receive an incorrect IP address.

Question 10

A network administrator receives a call from a user who cannot access any external websites from their wired workstation. The user can ping the default gateway successfully, but fails to ping 8.8.8.8. The administrator runs ipconfig /all on the workstation and sees an IP address of 192.168.1.50, subnet mask 255.255.255.0, and default gateway 192.168.1.1. What is the most likely cause of this issue?

Accepted Answer

The workstation has an incorrect default gateway configured.. The user can successfully ping 192.168.1.1, proving local IP connectivity to that device. However, the device at 192.168.1.1 may not be the correct default gateway for reaching external networks; the actual gateway router might be at a different IP (e.g., 192.168.1.254). This misconfiguration explains why pings to 8.8.8.8 fail even though the local gateway responds, as the workstation sends external traffic to the wrong next-hop address.

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The workstation has a duplicate IP address on the network.

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The workstation is connected to the wrong VLAN.

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The workstation has a DNS misconfiguration.

Question 11

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 faulty SFP must be removed first, then the new SFP installed, cable connected, and finally verification steps performed to confirm link and transceiver status using 'show interfaces' and 'show interfaces transceiver' commands.

Question 12

Drag and drop the following steps into the correct order to install a new fiber optic link between two switches, including SFP insertion and basic troubleshooting.

Accepted Answer

Insert SFP into Switch A, connect fiber cable to SFP on Switch A, then insert SFP into Switch B and connect fiber cable to SFP on Switch B, then verify link status on both switches.. The correct sequence is Option A: Insert SFP into Switch A, connect fiber cable, then repeat for Switch B, and finally verify link on both switches. This follows best practice to insert the SFP before attaching the fiber cable, which helps prevent dust contamination and ESD damage. Option B is incorrect because inserting both SFPs first leaves them exposed and increases risk of damage. Option C is wrong because connecting the cable before inserting the SFP can strain the connector and risk contamination. Option D is incorrect because verifying link on one switch before the other end is connected is futile – the link will not be up until both ends are properly installed.

Question 13

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

Accepted Answer

Physically replace the SFP, then connect the cable, and finally verify the link and check for errors.. The correct order is to physically replace the SFP first because installing the new module before connecting the cable prevents potential damage to the connector or fiber from inserting the cable into an empty port. After the SFP is seated, you connect the cable to establish the physical link. Finally, you verify the link status and check for errors (using commands like show interface) to confirm the replacement was successful and the link is operational. Wrong orders either verify before the change (making the verification meaningless) or connect the cable before installing the SFP, which can damage the equipment.

Question 14

Drag and drop the following steps into the correct order to install a new fiber optic cable and SFP module on a Cisco switch, then verify the interface status.

Accepted Answer

Insert the SFP module into the port while the switch is powered on. The correct procedure for installing a fiber optic cable and SFP module on a modern Cisco switch is to insert the SFP module into the port while the switch is powered on, as most Cisco switches support hot-swapping of SFP modules to minimize network downtime. Then, connect the fiber optic cable to the SFP module, ensuring proper alignment and locking. Finally, verify the interface status using 'show interfaces status' to confirm the link is up and operational. Powering down the switch is unnecessary and contradicts hot-swappable design, while connecting the cable before inserting the SFP or skipping the SFP module entirely are incorrect because the switch port requires an SFP to convert electrical signals to optical.

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

Disconnect the fiber cable from the SFP module.. To replace a faulty SFP, first disconnect the cable to avoid damage, then remove the old module, insert the new one, reconnect the cable, and finally verify the interface is operational.