dpns-shutdown: 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/sbin/dpns-shutdown - from package: dpm-name-server-mysql

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

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