sim_server: 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/sbin/sim_server - from package: krb5-devel

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

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