rollerd: 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/rollerd - from package: dnssec-tools

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

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