> A serial number has always been an increasing integer ... An unsigned 32-bit integer, to be specific. While I've always preferred and used the YYYYMMDDnn fo

> A serial number has always been an increasing integer ... An unsigned 32-bit integer, to be specific. While I've always preferred and used the YYYYMMDDnn format for the serial, I've noticed more and more zones using UNIX time for the serial in the last several years. I'm not sure where that "started" but my first guess would be some DNS server that uses something other than "BIND" zone files -- a MySQL database, perhaps? -- as its backend. > ... with no technical meaning assigned. To underscore this key point, consider the following statement from RFC 1982 (in the case where the serial is a 2-bit integer): It is undefined whether 2 > 0 or 0 > 2, and whether 1 > 3 or 3 > 1.