A replay attack occurs when an unauthorized user captures network traffic and then sends the communication to its original destination, acting as the original sender. To prevent replay attacks you can implement timestamps and sequence numbers.
References:
Dunkerley, D., & Samuelle, T. (2014). Secure Network Administration. In Mike Meyers' CompTIA Security Certification passport, fourth edition (exam SY0-401) (4th ed., p. 300). New York: McGraw-Hill Education.
