The IETF originally discouraged the production use of these two subnets. When the prefix length is not available, the larger network and the first subnet have the same address, which may lead to confusion. Similar confusion is possible broadcast address at the end of the last subnet. Therefore, reserving the subnet values consisting of all zeros and all ones on the public Internet was recommended, reducing the number of available subnets by two for each subnetting. This inefficiency was removed, and the practice was declared obsolete in 1995 and is only relevant when dealing with legacy equipment.