Juniper Exam JN0-231 Topic 1 Question 17 Discussion

The default value of the dead peer detection (DPD) interval for an IPsec VPN tunnel is 5 seconds. DPD is a mechanism that enables the IPsec device to detect if the peer is still reachable or if the IPsec VPN tunnel is still active. The DPD interval determines how often the IPsec device sends DPD packets to the peer to check the status of the VPN tunnel. A value of 5 seconds is a common default, but the specific value can vary depending on the IPsec device and its configuration.

Juniper Networks Technical Documentation: Configuring IPsec VPNs: https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/ipsec-vpn-overview-srx-series.html