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What your router's ARP table shows, and how to read it

Updated October 16, 2026 3 min read
TL;DRThe ARP table maps every device's local IP address to its MAC address. Your router keeps one automatically — here's where to find it and what each row means.

Short answer: the ARP table is the router’s running record of which MAC address currently answers for which local IP address. It’s how the router (and every device on your network) knows where to actually deliver a packet addressed to, say, 192.168.1.42.

What ARP is actually doing

ARP stands for Address Resolution Protocol. IP addresses and MAC addresses solve different problems — one marks where a device is on the network, the other identifies the physical device itself, as covered in MAC address vs IP address. The catch is that network hardware doesn’t deliver packets using an IP address. It delivers them using a MAC address. So whenever a device on your network wants to reach 192.168.1.42 and doesn’t already know which MAC that corresponds to, it broadcasts a question to the whole local network: “who has this IP?” The device that owns it answers with its MAC, and that pairing gets written into the ARP table.

Every device on the network keeps its own ARP table, including your router. The router’s copy is the useful one, because it covers every device currently or recently active on your WiFi and ethernet, all in one place.

Where to find it

Most consumer routers fold the ARP table into the same page as the connected-devices list, sometimes under a separate tab. Look for:

  • Attached Devices or Device List — usually shows IP and MAC together already
  • ARP Table or ARP Cache — a dedicated page on some brands, often under Advanced or Status
  • DHCP Client List — a related but distinct table; it records which IP a device was assigned by lease, not which MAC currently answers for it

If your router’s admin page doesn’t expose an ARP view directly, the connected-devices list is doing the same job in practice. How to see who is connected to your WiFi covers finding that page by brand.

Reading a row

A typical ARP entry has three columns: an IP address, a MAC address, and sometimes an interface or port. For example:

192.168.1.42    3C:5A:B4:12:9D:E7    eth0
192.168.1.57    A4:C3:F0:85:2B:11    wlan0

The IP is the address that device is currently using on your local network. The MAC is the hardware address answering for it. The interface, when shown, tells you whether that device is on WiFi or plugged in by ethernet.

The useful read here is pairing an unfamiliar IP with its MAC and checking the MAC’s vendor prefix with a MAC address lookup. A vendor name like “Espressif” or “Amazon Technologies” usually tells you more than a generic hostname does, and it’s the fastest way to connect a row in the ARP table to an actual gadget in the house.

Why the table changes on its own

ARP entries aren’t permanent. Most systems expire a mapping after it’s been idle for a few minutes, then re-request it the next time traffic needs to flow. That’s why an ARP table can show fewer devices than you’d expect: a smart plug that only phones home once an hour might not have a current entry if you happen to check between requests.

This also means the table reflects recent activity, not everything that’s ever connected. A device that was active an hour ago and has since gone idle, or physically left the network, drops out on its own without anyone deleting anything.

When this table actually matters

For most home networks, the ARP table is a diagnostic tool, not something to manage day to day. It’s worth checking when:

  • A device shows an IP you don’t recognize and you want its MAC to run through a vendor lookup
  • Two devices appear to be fighting over the same IP, which shows up as the address flipping between two different MACs in quick succession
  • You’re troubleshooting why a device on the same network can’t reach another one, since a missing or stale ARP entry can be the reason

Outside of troubleshooting, there’s nothing to configure. The table builds and expires itself as devices talk to each other.

Frequently asked questions

Why does my ARP table show fewer devices than my connected-devices list?

ARP entries expire after a short idle period, usually a few minutes, so a device that hasn't sent or received traffic recently can drop out of the table even though it's still associated with the WiFi. The connected-devices list tracks association, not recent traffic, so it tends to show more.

Can an ARP table be wrong?

Yes. A technique called ARP spoofing lets one device on the network claim another device's IP address, which corrupts the mapping for everyone. This matters on networks you don't fully trust, but it's not a practical concern on a typical home WiFi where every device belongs to the household.

Is the ARP table the same thing as the DHCP client list?

No, though they often sit side by side in a router's admin page. DHCP assigns the IP address and keeps a lease record; ARP separately maps that IP to a MAC address for delivering traffic on the local network. A router's device list usually blends both into one table.