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Chapter 13Once the host is synchronized, the stratum value shows a real value (below 15) thatis actually the number of ntp servers between you and the accurate clock (atomic,gps, or other type of radio clocks). In this case, the stratum 2 means that our uplinkntp host, which is a stratum 1 device, is directly connected to an accurate referenceclock. If the ntpd is out of sync, you will see stratum 16. Please see ntpq(8) manualpage for more information on querying from an ntp server.DNSDomain Name System (DNS) defined by RFC 1035 (and many other RFCs thatintroduce enhancements and extensions), is one of the protocols that is gluingthe whole internet together, and makes life easier by mapping names to hard-torememberIP addresses. Despite looking simple, DNS has evolved since its inventionback in 1983, and is getting more and more complex every day.Today's DNS servers are even able to map telephone numbers using the ENUMextension (RFC 3401 through 3404). As the DNS protocols evolves, the DNS relatedsoftware are also getting more and more complicated, facing more performance andsecurity challenges.BIND softwareFreeBSD 7 bundles ISC's BIND version 9.4.1 with the base system. BIND (ornamed(8) which is the actual daemon name) offers various modes of operations.There are also older versions of BIND still being used (8.x and 4.x). But the 9.4 seriesoffers the latest performance and security enhancements as well as support for IPv6and DNSSEC.If you are interested in running older versions or modified versions ofBIND, you can install them using ports system under the /usr/ports/dns directory.Operating ModesBIND can be used in two modes—Authoritative and Caching forwarder.Authoritative: In this mode, BIND has the mapping information in the zone files onthe disk, and answers queries based on the locally stored zone information.[ 215 ]