Understanding ip route Output — Line by Line, Word by Word

When debugging network issues on Linux, one of the most important commands is:

ip route

This command shows the routing table — the rules your system uses to decide where every network packet should go.

Let’s break down the following output in detail:

default via 192.168.1.1 dev wlp0s20f3 proto dhcp src 192.168.1.9 metric 600
192.168.1.0/24 dev wlp0s20f3 proto kernel scope link src 192.168.1.9 metric 600

No assumptions. No skipped words.

What a Routing Table Actually Is

A routing table is a list of instructions that answers one question:

“If a packet needs to go to this destination, which interface, gateway, and source IP should be used?”

Linux checks routes top-down, choosing the most specific match.

Line 1: The Default Route

default via 192.168.1.1 dev wlp0s20f3 proto dhcp src 192.168.1.9 metric 600

This line controls all traffic going outside your local network (internet traffic).

Word-by-word breakdown

• default
  • Matches any destination not covered by a more specific route
  • Used for internet traffic
• via
  • Indicates a gateway is required
• 192.168.1.1
  • The gateway IP
  • Usually your Wi-Fi router
• dev
  • Specifies the network interface
• wlp0s20f3
  • Wireless network interface name
  • (wl = wireless, rest is hardware naming)
• proto
  • Route origin
• dhcp
  • Route was added automatically by DHCP
  • Not manually configured
• src
  • Source IP address for outgoing packets
• 192.168.1.9
  • Your system’s IP address on this network
• metric
  • Route priority
  • Lower number = higher priority
• 600
  • Priority value used when multiple routes exist

Meaning in plain English

“For any destination not in the local network, send traffic through router 192.168.1.1 using Wi-Fi interface wlp0s20f3, with source IP 192.168.1.9.”

Line 2: The Local Network Route

192.168.1.0/24 dev wlp0s20f3 proto kernel scope link src 192.168.1.9 metric 600

This route handles local LAN traffic only.

Word-by-word breakdown

• 192.168.1.0/24
  • Destination subnet
  • Covers 192.168.1.1 → 192.168.1.254
  • /24 = subnet mask 255.255.255.0
• dev
  • Network interface used
• wlp0s20f3
  • Same Wi-Fi interface
• proto
  • Route origin
• kernel
  • Automatically added when interface came up
  • Not from DHCP or user config
• scope
  • Defines how far the route applies
• link
  • Destination is directly reachable
  • No gateway required
• src
  • Source IP for packets in this subnet
• 192.168.1.9
  • Your machine’s IP
• metric
  • Route priority
• 600
  • Same priority as default route

Meaning in plain English

“Any device inside 192.168.1.0/24 can be reached directly through Wi-Fi without using a router.”

Why Two Routes Are Needed

Linux needs both:

Without the local route → LAN breaks
Without the default route → Internet breaks

How Linux Chooses Between These Routes

Example: packet going to 192.168.1.50

• Matches 192.168.1.0/24
• Uses local route
• No gateway

Example: packet going to 8.8.8.8

• No specific subnet match
• Falls back to default route
• Uses router 192.168.1.1

Final Mental Model

Think of it like this:

• Local address? → send directly
• Anything else? → send to router
• Interface decides how
• Metric decides priority
• Source IP decides identity