--neg-ttl=<time>
Negative replies from upstream servers normally contain time-to-live
information in SOA records which dnsmasq uses for caching. If the
replies from upstream servers omit this information, dnsmasq does not
cache the reply. This option gives a default value for time-to-live
(in seconds) which dnsmasq uses to cache negative replies even in
the absence of an SOA record.