DNS supporting TTL values

Override the default minimum TTL value for fully qualified domain names (FQDNs) in the address book for DNS caching. This configuration ensures that DNS responses with TTL values lower or higher than 16 seconds are cached for their actual duration, rather than the default minimum of 16 seconds. The system maintains default behavior for backward compatibility unless reconfigured. This feature is particularly beneficial in environments where IP addresses change frequently, offering more accurate DNS resolution.