stunbdc: 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/stunbdc - from package: libnice

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

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