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Ping vs. Arping
Ping
Most Network Administrators have used the beloved Ping utility since they were young.
To "ping" a computer basically means to send an ICMP echo request to a remote computer, and then listen for an ICMP echo response.
By sending a request and listening for a response, ping is able to calculate how long the response took, much like SONAR, and display it back to the user.
Although computers are supposed to respond to ICMP echo requests, firewalls, both separate hardware devices and personal firewalls such as Windows Firewall, will often choose not to respond to ICMP echo requests.
Because of this, ping's effectiveness in determining if a host is up, or network latency, has severely diminished in recent years.
One of the great things about Ping is that because it works at the IP layer, the packets are routeable. Meaning that someone on a Private LAN, could "ping" a computer across the internet on the other side of the world, and still get a response from them.
Arping
Arping behaves exactly like ping in the idea that you can type "arping" an ip address and get a response back from it learning both network latency, and whether or not the remote host is currently up and running.
However, arping works at the Network Layer using ARP packets instead of ICMP echo requests.
Because it works at the Network or Hardware Layer, it is not routeable.
So, the only computers that someone can arping have to be on the same LAN.
Because of this limitation, it never gained the same widespread use as ping.
The Pros and Cons
| Routeable | Can be blocked by firewalls | |
| Ping | x | x |
| Arping |
As you see from the table, Ping is Routeable, but it can also be blocked by firewalls, making it less reliable. Arping is not routeable, but because of ARP Requests place in the TCP/IP stack, it can't be blocked.