void setRedundancyZone(InternalDistributedMember member, String redundancyZone) {
    if (redundancyZone != null && !redundancyZone.equals("")) {
      redundancyZones.put(member, redundancyZone);
    }
    if (member != getDistributionManagerId()) {
      String relationship = areInSameZone(getDistributionManagerId(), member) ? "" : "not ";
      logger.info("Member {} is {}equivalent or in the same redundancy zone.",
          member, relationship);
    }
  }
Return all of the InetAddress's that are equivalent to the given one (same host)

@param in host to match up
@return all the addresses thus equivalent
geode-core/src/main/java/org/apache/geode/distributed/internal/ClusterDistributionManager.java