dnsreplay: 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/dnsreplay - from package: pdns-tools

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

On Debian possible default full paths are:

/usr/bin/dnsreplay - from package: pdns-server

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

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