drill: 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/drill - from package: ldns

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

On Debian possible default full paths are:

/usr/bin/drill - from package: ldnsutils

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

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