Basic Routing and Switching Flashcards

A network switch receives an Ethernet frame on its Fa0/1 port. The destination MAC address of the frame is unknown to the switch. Which action will the switch take?

Answer: Forward the frame out all ports except for Fa0/1

When a switch receives a frame with a destination MAC address that is not in its MAC address table, its default behavior is to flood the frame. This means it forwards the frame out of every port in the same VLAN except for the port on which it was received, ensuring the frame reaches its destination if it exists on the network. The switch also adds the source MAC address and its corresponding port (Fa0/1) to its MAC address table.

What is the primary function of a default gateway in a host's IP configuration?

Answer: To provide a path for traffic destined for hosts on remote networks

The default gateway is the IP address of a router on the same local network as the host. When the host needs to send a packet to an IP address that is not on its local subnet, it sends the packet to the default gateway. The gateway router is then responsible for forwarding the packet toward its final destination.

A PC with IP address 192.168.1.10 needs to send data to a server with IP address 192.168.1.50 on the same local Ethernet network. The PC does not have the server's MAC address in its cache. Which protocol will the PC use to find the MAC address of the server?

Answer: ARP

The Address Resolution Protocol (ARP) is used to map a Layer 3 (IP) address to a Layer 2 (MAC) address on a local network. The PC will send out an ARP request broadcast on the local network asking for the MAC address associated with 192.168.1.50. The server will respond with an ARP reply containing its MAC address, allowing the PC to properly address the Ethernet frame.

A network administrator wants to improve security and network efficiency by segmenting a single physical switch into two separate logical networks: one for the 'Sales' department and one for the 'Engineering' department. Devices in one department should not be able to communicate directly with devices in the other at Layer 2. Which technology should be implemented?

Answer: Virtual Local Area Networks (VLANs)

VLANs allow a network administrator to logically segment a single physical switch into multiple virtual switches. Each VLAN is a separate broadcast domain. This prevents Layer 2 traffic from crossing between the configured VLANs, effectively isolating the 'Sales' and 'Engineering' departments as requested, even though they are connected to the same physical hardware.

Which of the following statements correctly differentiates the roles of switches and routers concerning traffic domains?

Answer: A switch forwards broadcast traffic by default, and each of its ports is a separate collision domain.

By default, a switch creates one large broadcast domain, meaning a broadcast frame sent by one device is forwarded to all other devices. However, switches segment collision domains; each port on a switch is its own collision domain. Routers, by contrast, do not forward broadcasts by default and are used to separate broadcast domains.

A network technician is troubleshooting a connectivity issue and suspects a routing problem. On a Cisco router, which command would be used to display the table that the router uses to determine the best path to a destination network?

Answer: show ip route

The `show ip route` command on a Cisco IOS device is used to display the IP routing table. This table contains a list of all known networks, the administrative distance and metric for those routes, and the next-hop IP address or exit interface used to reach them. It is the primary tool for verifying and troubleshooting a router's decision-making process.