Routing Tables: Something Your IT Person Pretends to Know About

This is not about the table that your router is sitting on

You should get some coffee before reading this. Photo by Luke Chesser

In computer networking, a routing table is a database that’s used by routers to determine the best path for forwarding network traffic to its destination. Essentially, a routing table contains information about different networks and the routes that can be taken to reach them. Let’s take a closer look at some of the key components of routing tables.

Destination Network

The destination network is the network address of a network to which the router can forward packets. In other words, it’s the address of the network that the packet is trying to reach.

Next Hop

The next hop, also known as the gateway in Windows, is the interface name or the address of the next router in the path to the destination network. In simple terms, it’s the next stop on the way to the destination network.

Hop and Hop Count

A hop is each router a packet must go through to get to the destination network. The hop count is the total number of routers a packet must travel through to get to its destination network. These terms are closely related since the hop count is simply the number of hops that a packet needs to travel through.

Metric

The metric is a numeric value that tells the router how “far away” the destination network is. This value is also known as the cost or distance. A lower metric means that the destination network is closer, while a higher metric means that it’s farther away.

Directly Connected Route

A directly connected route is a routing table entry that’s derived from a network to which one of the router’s network interfaces is directly connected. This means that the router is physically connected to the network, so it doesn’t need to go through any other routers to reach it.

Static Route

A static route is a routing table entry that’s entered manually by an administrator. This type of route is useful when a network administrator wants to define a specific path for traffic to take.

Administrative Distance

Administrative distance is a value assigned to a routing protocol that indicates its reliability compared to other routing protocols that might be in use on the same router. If a route is derived using two different routing protocols, the one with the least administrative distance is used.

Conclusion

Routing tables play a critical role in computer networking by helping routers determine the best path for forwarding network traffic. By understanding the key components of routing tables, network administrators can better manage their networks and ensure that data is transmitted quickly and efficiently.