ipa-server-certinstall: 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/sbin/ipa-server-certinstall - from package: ipa-server

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