Certainly, here's the continuation of the explanation regarding routing tables:

Understanding Routing Tables:

• In the earlier video on routing, you might have noticed references to something called a routing table. Routing tables are an integral part of how routers make decisions about forwarding data.
• Routing tables are used by routers to determine where to send data packets based on their destination IP addresses.
• Early routers were essentially regular computers with two network interfaces, bridging two networks and using manually updated routing tables.
• Even modern operating systems have routing tables that they consult before transmitting data. You can still build your own router today using a computer with two network interfaces and a manually updated routing table.

Components of a Routing Table:

• Routing tables vary based on the router's make and class, but they share common elements.

• The most basic routing table has four columns:

  

  1. Destination Network: Lists each network the router knows about, along with the network ID and subnet mask.
  2. Next Hop: This is the IP address of the next router that should receive data intended for the destination network. It can also state that the network is directly connected, requiring no additional hops.
  3. Total Hops: This is a critical aspect for routing. It indicates the number of hops (routers) it takes to reach the destination network. Routers aim to choose the shortest path for timely data delivery.
  4. Interface: Specifies which of the router's interfaces should be used to forward traffic to match the destination network.

Importance of Total Hops:

• Understanding how routing tables work involves grasping the concept of total hops.
• In complex networks like the Internet, multiple paths exist between points A and B.

• Routers strive to select the shortest path, but this can change due to factors like router failures, disconnections, congestion, or introduction of new routers.
• For each destination network and next hop, the router maintains information about the current distance (number of hops) to that destination. This helps the router determine whether it knows the best path or if an updated route is available.

Complexity of Routing Tables:

• Routing tables are usually straightforward, detailing the destination network, the next hop, the number of hops, and the outgoing interface.
• However, core Internet routers can have millions of rows in their routing tables.
• These tables are consulted for every single data packet flowing through a router as it determines the path to the packet's final destination.

Routing tables play a vital role in network communication, allowing routers to make informed decisions about how to forward data. If you have further questions or need more clarification, feel free to ask!