pdnsd: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/sbin/pdnsd - from package: pdnsd

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