dns-flood-detector: 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 Debian possible default full paths are:

/usr/bin/dns-flood-detector - from package: dns-flood-detector

You may install the required package with command apt-get install {package}

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