An NTP broadcast server sends periodic time updates to a broadcast address in a LAN. When a broadcast client is configured for NTP, that client can receive time information from the broadcasted NTP packets. Using broadcast packets can greatly reduce the NTP traffic on a network, especially in a network with many NTP clients.
To ensure that NTP broadcast clients get clock information from the correct NTP broadcast servers, with minimized risks from malicious NTP broadcast attacks, configure RSA Data Security, Inc. MD5 Message-Digest Algorithm authentication on both the NTP broadcast server and NTP clients.