NAME
  ZFOR - Z Fail-Over Resolver
DESCRIPTION
  ZFOR is a virtual hostname resolver that supports health checking and
  load-balancing. It could be used to take over some VIP works.
AUTHORS
  Xiaozhe Wang (chaoslawful [at] gmail [dot] com)
LICENSE AND COPYRIGHT
  ZFOR is licensed under the GPLv2 License
  Copyright (c) 2008, Yahoo! China Platform Works, Alibaba Inc. All
  rights reserved.
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are
  met:
  *   Redistributions of source code must retain the above copyright
  notice, this list of conditions and the following disclaimer.
  *   Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in the
  documentation and/or other materials provided with the distribution.
  *   Neither the name of the Yahoo! China EEEE Works, Alibaba Inc. nor
  the names of its contributors may be used to endorse or promote
  products derived from this software without specific prior written
  permission.
  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
  OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.