node_query6: 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/node_query6 - from package: thc-ipv6

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

Error in other languages:
node_query6: bevel nie gevind nie
node_query6: comandă negăsită
node_query6: comando não encontrado
node_query6: commande introuvable
node_query6: command not found
node_query6: käsku ei ole
node_query6: không tìm thấy lệnh
node_query6: komanda nerasta
node_query6: Kommando nicht gefunden.
node_query6: kommandot finns inte
node_query6: komut yok
node_query6: nie znaleziono polecenia
node_query6: níor aimsíodh an t-ordú
node_query6: no se encontró la orden
node_query6: no s'ha trobat l'ordre
node_query6: opdracht niet gevonden
node_query6: parancs nem található
node_query6: perintah tidak ditemukan
node_query6: príkaz nenájdený
node_query6: příkaz nenalezen
node_query6: команда не найдена
node_query6: командата не е открита
node_query6: 命令找不到
node_query6: コマンドが見つかりません