This KB article explores a common issue where the SRX device functions properly as an NTP (Network Time Protocol) client but encounters difficulties when configured as an NTP server simultaneously.

-The NTP client is not able to sync time.

-The SRX is working fine as an NTP client, but not as a server.

-TCPDUMP shows that there is no reply from the SRX.

-NTP source address is configured.

In SRX's NTP configuration hierarchy, if you explicitly specify the SRX NTP source-address, this action restricts the use of different source addresses for SRX NTP client and SRX NTP server. In other words, if you have explicitly set the NTP source address, it needs to be the same for both client and server operations.

To solve this:

1. Change the NTP IP on the Client Side: You can consider changing the NTP IP address on the client side to align it with the configured source address. Please ensure that there is reachability to the new NTP IP address. This change will harmonize the source address for both client and server operations.
2. Avoid Using Source-Address Parameter: An alternative solution is to avoid explicitly specifying the source-address parameter for NTP. By not configuring a source address, the SRX device will use its default behavior for NTP operations, which often simplifies the configuration and reduces the potential for conflicts.