100-150 Cisco Certified Support Technician Networking Exam Free Practice Exam Questions (2025 Updated)

Understanding How Layer 2 Switches Handle Unknown MAC Addresses

Switches operate at Layer 2 (Data Link Layer) of the OSI model and maintain a MAC address table (CAM table) to forward frames efficiently.

When a switch receives a frame, it checks its MAC address table to see if it knows the destination MAC address.

If the destination MAC address is not in the table (meaning the switch does not know which port leads to PC-C), the switch follows the flooding behavior.

What Happens When Switch1 Receives a Frame from PC-A to PC-C?

Switch1 checks its MAC table:

The source MAC (PC-A) is recorded in the table on port G0/1.

The destination MAC (PC-C) is not in the table.

Switch1 does not know where PC-C is:

It floods the frame out of all active ports except the port it was received on (G0/1).

This means the frame is sent to:

Switch2 (via G0/23)

PC-B (via G0/2)

Switch2 receives the frame and follows the same process:

If Switch2 has PC-C's MAC in its table, it forwards the frame appropriately.

If not, it floods the frame again until PC-C replies.

Once PC-C responds, Switch1 and Switch2 learn its MAC address and update their tables.

Why Other Options Are Incorrect:

❌ A. Switch1 queries Switch2 for the MAC address of PC-C.

Incorrect: Switches do not query other switches directly for MAC addresses. Instead, they rely on learning MAC addresses dynamically through frame forwarding.

❌ B. Switch1 drops the frame and sends an error message back to PC-A.

Incorrect: Switches do not drop frames for unknown MAC addresses. Instead, they flood the frames out all ports except the incoming port.

❌ D. Switch1 sends an ARP request to obtain the MAC address of PC-C.

Incorrect:

ARP (Address Resolution Protocol) is only used to resolve IP addresses to MAC addresses.

Since PC-A is sending a frame (Layer 2), not an IP packet (Layer 3), ARP is not involved here.

Conclusion

Since Switch1 does not know the destination MAC address, it floods the frame out all active ports except the port it was received on. This is the default behavior of Layer 2 switches when they encounter an unknown MAC address.

Thus, the correct answer is:✔ C. Switch1 floods the frame out all active ports except port G0/1.

References

Cisco CCNA 200-301 Official Guide – MAC Address Table & Frame Forwarding

RFC 894 – Standard for Ethernet Frame Forwarding

Cisco Networking Essentials – Switch Flooding Behavior

Statement A: "A detailed description of the fault." This is essential for support staff to understand the nature of the problem and begin troubleshooting effectively.

Statement C: "A description of the conditions when the fault occurs." This helps in reproducing the issue and identifying patterns that might indicate the cause of the fault.

Statement B: "Details about the computers connected to the network." While useful, this is not as immediately critical as understanding the fault itself and the conditions under which it occurs.

Statement D: "The actions taken to resolve the fault." This is important but typically follows the initial report.

Statement E: "The description of the top-down fault-finding procedure." This is more of a troubleshooting methodology than information typically included in an initial support ticket.

References:

Best Practices for Submitting Support Tickets: Support Ticket Guidelines

•Statement A: "The trace successfully reached the www.cisco.com server. " This is true as indicated by the "Trace complete" message at the end, showing that the trace has reached its destination.

•Statement C: "The IPv6 address associated with the www.cisco.com server is 2600:1408:c400:38d::b33. " This is true because the final hop in the trace, which is the destination, has this IPv6 address.

•Statement B: "The trace failed after the fourth hop." This is incorrect as the trace continues beyond the fourth hop, despite some intermediate timeouts.

•Statement D: "The routers at hops 5 and 6 are offline." This is not necessarily true. The routers might be configured to not respond to traceroute requests.

•Statement E: "The device sending the trace has IPv6 address 2600:1408:c400:38d::b33." This is incorrect; this address belongs to the destination server, not the sender.

References:

•Understanding Traceroute: Traceroute Guide

•1000BASE-T Cable: This refers to Gigabit Ethernet over twisted-pair cables (Cat 5e or higher).

•Connector: RJ-45 connectors are used for Ethernet cables, including those used for 1000BASE-T.

•Coax: Used for cable TV and older Ethernet standards like 10BASE2.

•RJ-11: Used for telephone connections.

•OS2 LC: Used for fiber optic connections.

References:

•Ethernet Standards and Cables: Ethernet Cable Guide

WPA2-Personal, also known as WPA2-PSK (Pre-Shared Key), is the wireless security option that uses a pre-shared key to authenticate clients. This method is designed for home and small office networks and doesn’t require an authentication server. Instead, every user on the network uses the same key or passphrase to connect1.

References :=

•What is a Wi-Fi Protected Access Pre-Shared Key (WPA-PSK)?

•Exploring WPA-PSK and WiFi Security

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•WPA2-Personal: This wireless security option uses a pre-shared key (PSK) for authentication. Each client that connects to the network must use this key to gain access. It is designed for home and small office networks where simplicity and ease of use are important.

•WPA2-Enterprise: Unlike WPA2-Personal, WPA2-Enterprise uses 802.1x authentication with an authentication server (such as RADIUS) and does not rely on a pre-shared key.

•802.1x: This is a network access control protocol for LANs, particularly wireless LANs. It provides an authentication mechanism to devices wishing to attach to a LAN or WLAN.

•802.1q: This is a networking standard that supports VLAN tagging on Ethernet networks and is not related to wireless security.

References:

•Cisco Documentation on WPA2 Security: Cisco WPA2

•Understanding Wireless Security: Wireless Security Guide

Three virtual machines are connected by a virtual network in the cloud.

Model: IaaS (Infrastructure as a Service)

Explanation: IaaS provides virtualized computing resources over the internet, including virtual machines, storage, and networks.

Users access a web-based graphics design application in the cloud for a monthly fee.

Model: SaaS (Software as a Service)

Explanation: SaaS delivers software applications over the internet, typically on a subscription basis, accessible via a web browser.

A company develops applications using cloud-based resources and tools.

Model: PaaS (Platform as a Service)

Explanation: PaaS provides a platform allowing customers to develop, run, and manage applications without dealing with the infrastructure.

IaaS (Infrastructure as a Service): Provides virtualized hardware resources that customers can use to build their own computing environments.

PaaS (Platform as a Service): Offers a platform with tools and services to develop, test, and deploy applications.

SaaS (Software as a Service): Delivers fully functional applications over the internet that users can access and use without managing the underlying infrastructure.

References:

Cloud Service Models: Understanding IaaS, PaaS, SaaS

NIST Definition of Cloud Computing: NIST Cloud Computing

In the provided image of the Cisco PoE switch, the ports identified with number 6 are the standard RJ-45 Ethernet ports typically found on switches that provide both data connectivity and Power over Ethernet (PoE). PoE ports are designed to supply power to devices such as IP phones, wireless access points, and other PoE-enabled devices directly through the Ethernet cable.

Ports:

•2: Console port (for management and configuration)

•3 and 4: Specific function ports (often for management)

•6: RJ-45 Ethernet ports (capable of providing PoE)

•7: SFP ports (for fiber connections, typically do not provide PoE)

Thus, the correct answer is C. Ports identified with number 6.

References :=

•Cisco Catalyst 2960-L Series Switches Data Sheet

•Cisco PoE Overview

The correct matching of the protocols to their examples is as follows:

DHCP: Assign the reserved IP address 10.10.10.200 to a web server at your company.

DNS: Perform a query to translate companypro.net to an IP address.

ICMP: Perform a ping to ensure that a server is responding to network connections.

Here’s how each protocol corresponds to its example:

DHCP (Dynamic Host Configuration Protocol) is used to assign IP addresses to devices on a network. In this case, DHCP would be used to assign the reserved IP address 10.10.10.200 to a web server.

DNS (Domain Name System) is used to translate domain names into IP addresses. Therefore, to translate companypro.net to an IP address, DNS would be utilized.

ICMP (Internet Control Message Protocol) is used for sending error messages and operational information indicating success or failure when communicating with another IP address. An example of this is using the ping command to check if a server is responding to network connections.

These protocols are essential for the smooth operation of networks and the internet.

Perform a query to translate companypro.net to an IP address.

DNS (Domain Name System): DNS is used to resolve domain names to IP addresses.

Assign the reserved IP address 10.10.10.200 to a web server at your company.

DHCP (Dynamic Host Configuration Protocol): DHCP is used to assign IP addresses to devices on a network.

Perform a ping to ensure that a server is responding to network connections.

ICMP (Internet Control Message Protocol): ICMP is used by network devices to send error messages and operational information, and it is the protocol used by the ping command.

DNS (Domain Name System): DNS translates human-friendly domain names like "companypro.net" into IP addresses that computers use to identify each other on the network.

DHCP (Dynamic Host Configuration Protocol): DHCP automatically assigns IP addresses to devices on a network, ensuring that no two devices have the same IP address.

ICMP (Internet Control Message Protocol): ICMP is used for diagnostic or control purposes, and the ping command uses ICMP to test the reachability of a host on an IP network.

References:

DNS Basics: What is DNS?

DHCP Overview: What is DHCP?

ICMP and Ping: Understanding ICMP

The command that will display the output provided, which includes capability codes, local interface details, device IDs, hold times, and platform port ID capabilities, is the show cdp neighbor command. This command is used in Cisco devices to display current information about neighboring devices detected by Cisco Discovery Protocol (CDP), which includes details such as the interface through which the neighbor is connected, the type of device, and the port ID of the device1.

References :=

•Cisco - show cdp neighbors

The provided output is from the Cisco Discovery Protocol (CDP) neighbor table. The show cdp neighbor command displays information about directly connected Cisco devices, including Device ID, Local Interface, Holdtime, Capability, Platform, and Port ID.

•A. show mac-address-table: Displays the MAC address table on the switch.

•C. show inventory: Displays information about the hardware inventory of the device.

•D. show ip interface: Displays IP interface status and configuration.

Thus, the correct answer is B. show cdp neighbor.

References :=

•Cisco CDP Neighbor Command

•Understanding CDP

Router

The show running-config command is used on a Cisco router to display the current operational settings that are actively configured in the router’s RAM. This command outputs all the configurations that are currently being executed by the router, which includes interface configurations, routing protocols, access lists, and other settings. Unlike show startup-config, which shows the saved configuration that the router will use on the next reboot, show running-config reflects the live, current configuration in use.

References := The information is supported by multiple sources that detail the use of Cisco commands, particularly the show running-config command as the standard for viewing the active configuration on a Cisco device123.

show running-config: This command displays the current configuration running on the router. It includes all the operational settings and configurations applied to the router.

show protocols: This command shows the status of configured protocols on the router but not the entire configuration.

show startup-config: This command displays the configuration saved in NVRAM, which is used to initialize the router on startup, but not necessarily the current running configuration.

show version: This command provides information about the router's software version, hardware components, and uptime but does not display the running configuration.

References:

Cisco IOS Commands: Cisco IOS Commands

To list the IPv4 addresses associated with the host name www.companypro.net, you should use the following command:

nslookup www.companypro.net

This command will query the DNS servers to find the IP address associated with the hostname provided. If you want to ensure that it returns the IPv4 address, you can specify the -type=A option, which stands for Address records that hold IPv4 addresses1. However, the nslookup command by default should return the IPv4 address if available.

To list the IPv4 addresses associated with the host name www.companypro.net , you should use the nslookup command.

Command: nslookup

Target: www.companypro.net

So, the completed command is:

nslookup www.companypro.net

nslookup: This command is used to query the Domain Name System (DNS) to obtain domain name or IP address mapping or for any other specific DNS record.

www.companypro.net : This is the domain name you want to query to obtain its associated IP addresses.

References:

Using nslookup: nslookup Command Guide