This post shows three IPv4 address blocks that are available for documentation purposes. Predefined address ranges for documentation and examples eliminate the risk of conflicts and misunderstandings caused by the usage of addresses assigned for another reason.
Below are the blocks you can use for documentation:
192.0.2.0/24 (TEST-NET-1),
198.51.100.0/24 (TEST-NET-2),
203.0.113.0/24 (TEST-NET-3)