100-150 Questions and Answers

Out-of-band management

When a Cisco switch is not accessible from the network, the recommended out-of-band method to access its running configuration is through the console port. Out-of-band management involves accessing the network device through a dedicated management channel that is not part of the data network. The console port provides direct access to the switch’s Command Line Interface (CLI) without using the network, which is essential when the switch cannot be accessed remotely via the network12.

References :=

Out-of-band (OOB) network interface configuration guidelines

Out of band management configuration

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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

The CIDR (Classless Inter-Domain Routing) notation for the subnet mask 255.255.252.0 is /22. This notation indicates that the first 22 bits of the IP address are used for network identification, and the remaining bits are used for host addresses within the network1.

References :=

•Subnet Cheat Sheet – 24 Subnet Mask, 30, 26, 27, 29, and other IP Address CIDR Network References

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•Subnet Mask to CIDR Notation: The given subnet mask is 255.255.252.0. To convert this to CIDR notation:

•Convert the subnet mask to binary: 11111111.11111111.11111100.00000000

•Count the number of consecutive 1s in the binary form: There are 22 ones.

•Therefore, the CIDR notation is /22.

References:

•Understanding Subnetting and CIDR: Cisco CIDR 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

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

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

Statement 1: Low bandwidth can increase network latency.

True: Low bandwidth can result in increased network latency because the network may become congested, leading to delays in data transmission.

Statement 2: High levels of network latency decrease network bandwidth.

False: High levels of network latency do not decrease the available network bandwidth, but they do affect the perceived performance and throughput of the network.

Statement 3: You can increase throughput by decreasing network latency.

True: Decreasing network latency can increase throughput because data can be transmitted more quickly and efficiently without delays.

Bandwidth vs. Latency: Bandwidth refers to the maximum rate at which data can be transferred over a network path. Latency is the time it takes for a data packet to travel from the source to the destination.

Low bandwidth can cause network congestion, which can increase latency as packets wait to be transmitted.

High latency does not reduce the actual bandwidth but can affect the overall performance and efficiency of data transmission.

Reducing latency can lead to higher throughput because the network can handle more data in a given period without delays.

References:

Network Performance Metrics: Cisco Network Performance

Understanding Bandwidth and Latency: Bandwidth vs. Latency