iptest: 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:

/usr/bin/iptest - from package: python-ipython-tests

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

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