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Routing Table Basics Explained

See, step by step, how a packet finds its way to its destination.

What a Routing Table Is

A list of path information that a router or computer consults to send packets to their destination. It's organized as rules like "for this destination network, send it this way," and every time a packet arrives, the device checks this table to decide where to send it next.

Destination Network and Next Hop

Each entry in a routing table is essentially a rule: "to reach this destination network, send the packet to this next device (the next hop)." If the destination isn't on a directly connected network, the packet gets handed to the next router, which repeats the same lookup process.

The Default Route

The catch-all route used when no entry in the table exactly matches a packet's destination β€” it covers "everywhere else." On a home network, the router's gateway out to the internet usually serves as this default route.

Metric (Route Priority)

A value used to decide which path to prefer when multiple routes exist to the same destination. In general, a lower number means a higher-priority route.

Static Routing

Routes entered and fixed manually by an administrator. It keeps small networks simple and predictable, but every time the network's structure changes, someone has to update the entries by hand.

Dynamic Routing

Routers exchange information with each other over a routing protocol and automatically calculate and update the best paths. This is the norm on large networks or internet backbone segments where the topology changes frequently.

Checking Your Own PC's Routing Table

On Windows, type route print into Command Prompt; on Mac or Linux, running netstat -rn or ip route in a terminal shows your system's current routing table.

How internet-scale dynamic routing works

The routing table concept described here operates within a single network or a small set of connected networks. At internet scale, routers run protocols like BGP to exchange reachability information across thousands of independently operated networks, which is a much larger and more coordination-heavy process than the static or dynamic routing used inside a home or office.

Other handy commands for checking your network

Beyond looking at the routing table, a handful of other built-in command-line tools β€” like one that traces the hop-by-hop path to a destination, or one that checks basic reachability β€” are worth knowing when you're troubleshooting a connection issue on your own PC.

Frequently Asked Questions

Does a home router have a routing table too?

Yes, though it's usually very simple β€” mostly just the internal network and a default route out to the internet β€” so there's rarely anything a typical user needs to touch.

The output of route print or ip route looks too complicated.

Start by looking only at the destination, netmask, gateway, and interface columns. Most lines boil down to just two things: the default route (0.0.0.0) and the route to your own local network.