adnshost: 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
/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/adnshost - from package: adns-tools
/usr/lib/debug/usr/bin/adnshost - from package: libadns1-dbg

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