dns2tcpd: 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 Debian possible default full paths are:

/usr/bin/dns2tcpd - from package: dns2tcp

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

Error in other languages:
dns2tcpd: bevel nie gevind nie
dns2tcpd: comandă negăsită
dns2tcpd: comando não encontrado
dns2tcpd: commande introuvable
dns2tcpd: command not found
dns2tcpd: käsku ei ole
dns2tcpd: không tìm thấy lệnh
dns2tcpd: komanda nerasta
dns2tcpd: Kommando nicht gefunden.
dns2tcpd: kommandot finns inte
dns2tcpd: komut yok
dns2tcpd: nie znaleziono polecenia
dns2tcpd: níor aimsíodh an t-ordú
dns2tcpd: no se encontró la orden
dns2tcpd: no s'ha trobat l'ordre
dns2tcpd: opdracht niet gevonden
dns2tcpd: parancs nem található
dns2tcpd: perintah tidak ditemukan
dns2tcpd: príkaz nenájdený
dns2tcpd: příkaz nenalezen
dns2tcpd: команда не найдена
dns2tcpd: командата не е открита
dns2tcpd: 命令找不到
dns2tcpd: コマンドが見つかりません