getdnskeys: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/getdnskeys - from package: dnssec-tools

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