ip2host: 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 Debian possible default full paths are:

/usr/bin/ip2host - from package: ip2host

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

Error in other languages:
ip2host: bevel nie gevind nie
ip2host: comandă negăsită
ip2host: comando não encontrado
ip2host: commande introuvable
ip2host: command not found
ip2host: käsku ei ole
ip2host: không tìm thấy lệnh
ip2host: komanda nerasta
ip2host: Kommando nicht gefunden.
ip2host: kommandot finns inte
ip2host: komut yok
ip2host: nie znaleziono polecenia
ip2host: níor aimsíodh an t-ordú
ip2host: no se encontró la orden
ip2host: no s'ha trobat l'ordre
ip2host: opdracht niet gevonden
ip2host: parancs nem található
ip2host: perintah tidak ditemukan
ip2host: príkaz nenájdený
ip2host: příkaz nenalezen
ip2host: команда не найдена
ip2host: командата не е открита
ip2host: 命令找不到
ip2host: コマンドが見つかりません