dtconf: 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/dtconf - from package: dnssec-tools

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

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