2.1 Routing Technologies

Question 1

What is the primary role of a router in a network?

Answer 1

To evaluate incoming traffic, determine the destination, and forward it through the appropriate interface using its routing table.

Transcript: “The job of a router is to evaluate incoming traffic… and then send it out the appropriate interface.” (0:00–0:11)

Question 2

What is a routing table and why is it important?

Answer 2

A routing table is a data table stored in a router that lists routes to network destinations. It’s crucial for determining the best path for packet forwarding.

Transcript: “To be able to make this decision about where traffic goes, we need a routing table.” (0:19–0:22)

Question 3

What is administrative distance and why is it used?

Answer 3

Administrative distance is a value used to rank the trustworthiness of different routing protocols. Lower values are preferred.

Transcript: “Different routing protocols are assigned different administrative distances… the lower the administrative distance, the better the route…” (7:06–7:40)

Question 4

What is a routing metric and how is it used?

Answer 4

A routing metric is a value used by a routing protocol to determine the best path. Different protocols use different metrics and they are not comparable across protocols. Choose lowest metric.

Transcript: “Routing metrics are an internal value that are used by the routing protocol itself… cannot compare routing metrics across different routing protocols.” (8:25–8:59)

Question 5

What is a virtual IP (VIP) address and what is it used?

Answer 5

A VIP is a shared IP used by redundant routers to provide seamless failover if the active router fails.

Transcript: “Create a virtual IP address for the router that’s in use… if the primary router disappears, we can move that virtual IP to another router…” (11:55–12:05)

Question 6

What is FHRP and how does it support high availability?

Answer 6

FhRB (First Hop Redundancy Protocol) allows automatic failover to a standby router using a VIP, ensuring uninterrupted connectivity.

Transcript: “In this particular example, we’re going to use the first hop redundancy protocol, or FHRP, in conjunction with a virtual IP address…” (12:41–12:47)

Question 7

What are subinterfaces on a router?

Answer 7

Subinterfaces are logical interfaces created on a physical interface to support multiple VLANs over a trunk link.

Often referenced with the physical
* Interface Ethernet1/1
* Subinterface Ethernet 1/1.20
* Subinterface Ethernet 1/1.20
* Subinterface Ethernet 1/1.100

Transcript: “You can assign multiple interfaces to a single physical interface… referred to as subinterfaces.” (14:01–14:11)

Question 8

How do subinterfaces support VLAN routing?

Answer 8

Each subinterface corresponds to a VLAN and is configured with its own IP address and subnet mask, enabling inter-VLAN routing.

Transcript: “We can set different configurations for each of these subinterfaces so that we can reference them with the appropriate IP address for that VLAN.” (15:04–15:08)

Question 9

Explain each of these components in this line in a routing table

Answer 9

Route Code: Shows what protocol was used to receive this information

Subnet ID with Prefix Length: destination subnet

Adminstrative Distance: Value to rank trustworthiness of a specific routing protocols (lower number is better)

Metric: Value used by a routing protocol to determine the best path (choose lowest metric)

Next Hop: The destination to send this traffic if we needed to go to the location shown in the subnet IP w/ prefix

Route Timestamp: How long the route has been active inside this routing table

Outgoing Interface: The interface by which we would reach the next hop