dnsscope: 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 CentOS possible default full paths are:

/usr/bin/dnsscope - from package: pdns-tools

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/dnsscope - from package: pdns-server

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

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