arping: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/sbin/arping - from package: iputils
/usr/sbin/arping - from package: iputils

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/sbin/arping - from package: arping
/usr/bin/arping - from package: iputils-arping

You may install the required package with command apt-get install {package}

Error in other languages:
arping: bevel nie gevind nie
arping: comandă negăsită
arping: comando não encontrado
arping: commande introuvable
arping: command not found
arping: käsku ei ole
arping: không tìm thấy lệnh
arping: komanda nerasta
arping: Kommando nicht gefunden.
arping: kommandot finns inte
arping: komut yok
arping: nie znaleziono polecenia
arping: níor aimsíodh an t-ordú
arping: no se encontró la orden
arping: no s'ha trobat l'ordre
arping: opdracht niet gevonden
arping: parancs nem található
arping: perintah tidak ditemukan
arping: príkaz nenájdený
arping: příkaz nenalezen
arping: команда не найдена
arping: командата не е открита
arping: 命令找不到
arping: コマンドが見つかりません