zone2json: 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/zone2json - from package: pdns

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

Error in other languages:
zone2json: bevel nie gevind nie
zone2json: comandă negăsită
zone2json: comando não encontrado
zone2json: commande introuvable
zone2json: command not found
zone2json: käsku ei ole
zone2json: không tìm thấy lệnh
zone2json: komanda nerasta
zone2json: Kommando nicht gefunden.
zone2json: kommandot finns inte
zone2json: komut yok
zone2json: nie znaleziono polecenia
zone2json: níor aimsíodh an t-ordú
zone2json: no se encontró la orden
zone2json: no s'ha trobat l'ordre
zone2json: opdracht niet gevonden
zone2json: parancs nem található
zone2json: perintah tidak ditemukan
zone2json: príkaz nenájdený
zone2json: příkaz nenalezen
zone2json: команда не найдена
zone2json: командата не е открита
zone2json: 命令找不到
zone2json: コマンドが見つかりません