Password policy or more reasons, such as being easily guessed, following a common pattern, or public disclosure from previous data breaches. Common examples are Password1, Qwerty123, or Qaz123wsx. Some policies require users to change passwords periodically, often every 90 or 180 days. The benefit of password expiration, however, is debatable. Systems that implement such policies sometimes prevent users from picking a password too close to a previous selection. This policy can often backfire. Some users find it hard to devise "good" passwords that are also easy to remember, so if people are required to choose many passwords because they have to change
Most recent common ancestor Most recent common ancestor In biology and genealogy, the most recent common ancestor (MRCA, also last common ancestor (LCA), or concestor) of any set of organisms is the most recent individual from which all the organisms are directly descended. The term is also used in reference to the ancestry of groups of genes (haplotypes) rather than organisms. The MRCA of a set of individuals can sometimes be determined by referring to an established pedigree. However, in general, it is impossible to identify the exact MRCA of a large set of individuals, but an estimate of the time at which the