Unexpected TTL

[stodge]

I'm using jmDNS 3.5.9 in two applications; an emulator (essentially a server) and a client. The server and client are both running on the same Windows 11 PC.

The emulator manages the services; each service has a button that the user presses to create and register that service. The 5 services are:

• SERVICE1._TESTNET._udp.local
• SERVICE2._TESTNET._udp.local
• SERVICE3._TESTNET._udp.local
• SERVICE4._TESTNET._udp.local
• SERVICE5._TESTNET._udp.local

The client automatically subscribes to the service type (e.g., "_TESTNET._udp.local").

My steps are:

• Start Wireshark capture, filter on mdns
• Start emulator
  • User registers first service (let's just call it SERVICE1 for clarity and brevity here) on emulator
• Monitor PCAP
  • For SERVICE1, TTL=2 minutes
• Start client - automatically subscribes to service type
  • Wait for the client to detect SERVICE1
  • User registers 4 other services (e.g., SERVICE2, SERVICE3 and SERVICE4) on emulator
• Monitor PCAP
  • SERVICE1 is republished, TTL=1 hour <=== ????
  • For services SERVICE2, SERVICE3 and SERVICE4, TTL=2 minutes

There are two mDNS cache flush records for SERVICE1 after the client starts. The first record has a TTL of 1 hour, and the second record (re-transmitted response) has a TTL of 2 minutes.

I'm trying to override the default TTL with:

        // Override the default TTL.
        DNSStateTask.setDefaultTTL(120);

        Properties props = System.getProperties();
        props.setProperty("net.dns.ttl", String.valueOf(120));

Is there any way to always set the TTL to a specific value for a service or service type?