DNS-Orly
Материал из fidoman.ru
Extension for DNS client protocol
If client loses communication with host of interest, it can re-ask its IP from DNS with flag o'rly. On receive of this flag client's DNS cache must re-query the hostname to check the possibility that host's IP is changed. TTL for cache of orlied record (in case of many or repeation orly queries) should be kept reasonable small, e.g. 30-90 seconds.
