The Cisco Certified Support Technician Networking Exam (100-150)

To determine if you can reach the router, you should use the ping command followed by the IP address of the router. The ping command is a network utility used to test the reachability of a host on an Internet Protocol (IP) network and to measure the round-trip time for messages sent from the originating host to a destination computer.

The Default Gateway in the ipconfig results is typically the router’s IP address in a home or small office network. In this case, the Default Gateway is 192.168.0.1 , which is the address you would ping to check connectivity to the router.

References :=

How to Use the Ping Command

Testing Network Connectivity with the Ping Command

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To determine if you can reach the router, you should use the ping command with the IP address of the router.

Command : ping

Target : 192.168.0.1

So, the completed command is:

ping 192.168.0.1

Step by Step Comprehensive and Detailed Explanation :

ping : The ping command sends ICMP Echo Request messages to the target IP address and waits for an Echo Reply. It is commonly used to test the reachability of a network device.

192.168.0.1 : This is the IP address of the default gateway (the router) as shown in the ipconfig output. Pinging this address will help determine if the computer can communicate with the router.

References :

Using the ping Command: ping Command Guide

OSI model

During the data encapsulation process, the Data Link layer of the OSI model is responsible for adding a header that contains MAC addressing information and a trailer used for error checking. The header typically includes the source and destination MAC addresses, while the trailer contains a Frame Check Sequence (FCS) which is used for error detection 1 .

The Data Link layer ensures that messages are delivered to the proper device on a LAN using hardware addresses and translates messages from the Network layer into bits for the Physical layer to transmit. It also controls how data is placed onto the medium and is received from the medium through the physical hardware.

References :=

The OSI Model – The 7 Layers of Networking Explained in Plain English

OSI Model - Network Direction

Which layer adds both header and trailer to the data?

What is OSI Model | 7 Layers Explained - GeeksforGeeks

SFTP, or Secure File Transfer Protocol, is a protocol that allows for secure file transfer capabilities between networked hosts. It is a secure extension of the File Transfer Protocol (FTP). SFTP encrypts both commands and data, preventing passwords and sensitive information from being transmitted openly over the network. It is typically used for secure file transfers over the internet and is built on the Secure Shell (SSH) protocol1.

References :=

• What Is SFTP? (Secure File Transfer Protocol)

• How to Use SFTP to Safely Transfer Files: A Step-by-Step Guide

• Secure File Transfers: Best Practices, Protocols And Tools

The Secure File Transfer Protocol (SFTP) is a secure version of the File Transfer Protocol (FTP) that uses SSH (Secure Shell) to encrypt all commands and data. This ensures that sensitive information, such as usernames, passwords, and files being transferred, are securely transmitted over the network.

• ICMP (Internet Control Message Protocol) is used for network diagnostics and is not designed for file transfer.

• NTP (Network Time Protocol) is used to synchronize clocks between computer systems and is not related to file transfer.

• HTTP (HyperText Transfer Protocol) is used for transmitting web pages over the internet and does not inherently provide secure file transfer capabilities.

Thus, the correct protocol that allows secure uploading of files to another computer on the internet is SFTP.

References :=

• Cisco Learning Network

• SFTP Overview (Cisco)

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

A firewall can direct all web traffic to a specific IP address .

True : Firewalls can be configured to perform Network Address Translation (NAT) and port forwarding, which can direct all web traffic (typically on port 80 and 443) to a specific internal IP address.

A firewall can block traffic to specific ports on internal computers .

True : Firewalls can be configured with access control lists (ACLs) or rules to block traffic to specific ports on internal computers, enhancing security by restricting unwanted or harmful traffic.

A firewall can prevent specific apps from running on a computer .

False : Firewalls typically control traffic flow and do not prevent specific applications from running on a computer. Application control is usually managed by endpoint security software or application control systems.

Directing Web Traffic : Firewalls can manage traffic redirection using NAT and port forwarding rules to route web traffic to designated servers or devices within the network.

Blocking Specific Ports : Firewalls can enforce security policies by blocking or allowing traffic based on port numbers, ensuring that only permitted traffic reaches internal systems.

Application Control : While firewalls manage network traffic, preventing applications from running typically requires software specifically designed for endpoint protection and application management.

References :

Understanding Firewalls: Firewall Capabilities

Network Security Best Practices: Network Security Guide

The AAA service security model consists of three components: Authentication, Authorization, and Accounting.

• Authentication: This is the process of verifying the identity of a user or device. It ensures that only legitimate users can access the network or service.

• Authorization: This determines what an authenticated user is allowed to do or access within the network.

• Auditing/Accounting: This component tracks the actions of the user, including what resources they access and what changes they make.

Thus, the correct answer is C. Authentication.

References :=

• Cisco AAA Overview

• Understanding AAA (Authentication, Authorization, and Accounting)

• Statement B: " The same default gateway IPv4 address is configured on each host on the local network. " This is true because all hosts on the same local network (subnet) use the same default gateway IP address to send packets destined for other networks.

• Statement D: " The default gateway is the IPv4 address of the router interface connected to the same local network as the host. " This is true because the default gateway is the IP address of the router ' s interface that is directly connected to the local network.

• Statement A: " The IPv4 address of the default gateway must be the first host address in the subnet. " This is not necessarily true. The default gateway can be any address within the subnet range.

• Statement C: " The default gateway is the Loopback0 interface IPv4 address of the router connected to the same local network as the host. " This is not true; the default gateway is the IP address of the router ' s physical or logical interface connected to the local network.

• Statement E: " Hosts learn the default gateway IPv4 address through router advertisement messages. " This is generally true for IPv6 with Router Advertisement (RA) messages, but not typically how IPv4 hosts learn the default gateway address.

References:

• Cisco Default Gateway Configuration: Cisco Default Gateway

• 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

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