lsrealm: 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/lsrealm - from package: dnssec-tools

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