fdnscname: 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/fdnscname - from package: firedns

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

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