Explanation: According to the OSI model, the Network layer (Layer 3) is responsible for logical addressing and routing of packets. This layer adds logical addressing information (such as IP addresses) to the data received from the Transport layer and determines the best path for data to travel through the network based on routing protocols like OSPF or EIGRP.

Explanation: Spanning Tree Protocol (STP) is used to prevent loops in Ethernet networks by actively blocking redundant paths, thus ensuring a loop-free topology. STP calculates the shortest path to the root bridge and blocks redundant paths to avoid loops while allowing for network redundancy.

Explanation: The “privileged EXEC mode” in Cisco IOS provides access to all available commands on the device, allowing administrators to perform advanced configuration tasks such as modifying routing tables, configuring access control lists (ACLs), and managing system resources. This mode is typically accessed using the “enable” command after logging into the device.

Explanation: Subnetting divides a larger network into smaller, more manageable subnetworks, thereby increasing the number of available IP addresses within the network. This helps in efficient address allocation and reduces IP address wastage.

Explanation: Cisco Catalyst switches are commonly used to connect multiple network segments within a LAN and forward data based on MAC addresses at Layer 2 of the OSI model.

Explanation: Traceroute is a diagnostic tool used to identify the route that packets take from the source to the destination. It shows the IP addresses of all the routers that the packets pass through, helping in diagnosing connectivity issues along the path.

Explanation: OSPF (Open Shortest Path First) is a link-state routing protocol that typically uses the Dijkstra algorithm to calculate the best path to a destination network based on metrics such as cost or bandwidth.

Explanation: The “global configuration mode” in Cisco IOS is used to configure device-specific settings and parameters, such as interface configurations, routing protocols, and device hostname. Commands entered in this mode affect the entire device.

Explanation: SSH (Secure Shell) provides encrypted and secure remote access to Cisco devices for configuration and management. It is preferred over Telnet due to its enhanced security features, including encryption of data transmitted over the network.

Explanation: VLANs are used to segment a switched network into smaller broadcast domains, thereby reducing the broadcast traffic on each segment and improving network performance and security. Each VLAN operates as a separate logical network, even though devices may physically connect to the same switch.

Explanation: A loopback interface is a virtual interface on a Cisco device that allows for testing and troubleshooting without requiring physical connectivity to the network. It can be configured with an IP address and used to generate simulated network traffic for testing purposes.

Explanation: The first step in the troubleshooting process is to identify the problem by gathering information, analyzing symptoms, and determining the scope and impact of the issue. Once the problem is clearly defined, appropriate steps can be taken to resolve it.

Explanation: Cisco ISR (Integrated Services Router) routers are typically used to connect different networks together and forward data based on IP addresses at Layer 3 of the OSI model.

Explanation: The ping command is used to send ICMP Echo Request messages to a destination device and measure the round-trip time for the packets to travel to the destination and back. It helps in testing network connectivity and identifying potential latency issues.

Explanation: DHCP is used to dynamically assign IP addresses, as well as other network configuration parameters (such as subnet mask, default gateway, DNS server) to devices on a network. This simplifies network administration by automating the IP address assignment process.

Explanation: RIP is classified as a distance vector routing protocol, which uses hop count as its metric for path selection. It periodically broadcasts routing information to its neighboring routers.

Explanation: Telnet transmits data in clear text, making it susceptible to eavesdropping and interception. For this reason, it is considered less secure compared to SSH, which provides encrypted communication.

Explanation: Trunking is used to forward traffic between different VLANs (Virtual Local Area Networks) over a single physical link, allowing multiple VLANs to communicate with each other within a network.

Explanation: Interface configuration mode in Cisco IOS allows administrators to modify interface parameters such as IP addresses, subnet masks, and other interface-specific settings.

Explanation: Documentation in network configuration and troubleshooting provides a record of changes made to network configurations, which is crucial for maintaining an accurate and up-to-date inventory of network devices and configurations, as well as for troubleshooting historical issues.

Explanation: VLAN tagging adds information to Ethernet frames to identify the VLAN membership of the frame. This allows switches to correctly forward frames to the appropriate VLANs based on the tagging information.

Explanation: The “copy running-config startup-config” command is used to save the current running configuration of a Cisco device to non-volatile memory (NVRAM), ensuring that the configuration is retained across reboots.

Explanation: Establishing a hypothesis involves formulating a theory about the root cause of the problem based on available information and observations. This helps guide the troubleshooting process towards identifying and resolving the underlying issue.

Explanation: Cisco ISR (Integrated Services Router) routers are commonly used in small to medium-sized business networks due to their versatility, supporting various WAN connectivity options such as DSL, Ethernet, and T1/E1.

Explanation: A service-level agreement (SLA) is a contract between a service provider and a customer that defines the expected level of service, including uptime, performance, and support, as well as remedies in case of service disruptions or failures.

Explanation: SNMP (Simple Network Management Protocol) is used to monitor and manage network devices, gather information for performance monitoring, and detect faults by polling devices for status information and receiving traps or alerts.

Explanation: A router is a networking device that forwards data packets between different networks or subnetworks based on IP addresses, enabling communication between devices on different LANs or subnets.

Explanation: Telnet is deprecated due to security vulnerabilities, such as transmitting data in clear text, making it susceptible to eavesdropping and interception. It is recommended to replace Telnet with more secure alternatives like SSH.

Explanation: The Transport layer (Layer 4) is responsible for establishing, maintaining, and terminating connections between devices, ensuring reliable end-to-end communication by providing services such as error detection, flow control, and data segmentation.

Explanation: The “privileged EXEC mode” in Cisco IOS provides access to all available commands on the device, allowing administrators to perform advanced configuration tasks such as modifying routing tables, configuring access control lists (ACLs), and managing system resources. This mode is typically accessed using the “enable” command after logging into the device.