mkdumprd: 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:

/sbin/mkdumprd - from package: kexec-tools

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

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