msntest: 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/msntest - from package: libmsn

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

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