This read-create IpAddress, defaulting to 0.0.0.0, configures a second IP address this PTP clock will accept as a valid master, providing redundancy alongside zhonePtpConfigAcceptableMaster1. An admin sets this to a backup grandmaster's address so the clock can fail over to a second trusted time source if the primary becomes unavailable. For example, an admin sets this to 10.0.0.2 as a standby grandmaster in case the primary at 10.0.0.1 goes offline.