dtconfchk: 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/dtconfchk - from package: dnssec-tools

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

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