zone2sql: 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/zone2sql - from package: pdns

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

On Debian possible default full paths are:

/usr/bin/zone2sql - from package: pdns-server

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

Error in other languages:
zone2sql: bevel nie gevind nie
zone2sql: comandă negăsită
zone2sql: comando não encontrado
zone2sql: commande introuvable
zone2sql: command not found
zone2sql: käsku ei ole
zone2sql: không tìm thấy lệnh
zone2sql: komanda nerasta
zone2sql: Kommando nicht gefunden.
zone2sql: kommandot finns inte
zone2sql: komut yok
zone2sql: nie znaleziono polecenia
zone2sql: níor aimsíodh an t-ordú
zone2sql: no se encontró la orden
zone2sql: no s'ha trobat l'ordre
zone2sql: opdracht niet gevonden
zone2sql: parancs nem található
zone2sql: perintah tidak ditemukan
zone2sql: príkaz nenájdený
zone2sql: příkaz nenalezen
zone2sql: команда не найдена
zone2sql: командата не е открита
zone2sql: 命令找不到
zone2sql: コマンドが見つかりません