dns_server_test: 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/lib/plainbox-providers-1/checkbox/bin/dns_server_test - from package: plainbox-provider-checkbox

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

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