Wikipedia
.za
.za is the Internet country code top-level domain ( ccTLD) for South Africa. It is administered by the .za Domain Name Authority (ZADNA).
None of the official names for South Africa can be abbreviated to ZA, which is an abbreviation of the Dutch Zuid-Afrika. Dutch was considered an official language in the Union of South Africa until 1961; it subsequently lost its synonymous status with Afrikaans in 1983. Suid-Afrika is the standard spelling in Afrikaans, however, the .sa domain is used by Saudi Arabia and, incidentally, Zuid-Afrika has a history of usage: ZAR serves as the ISO 4217 currency code for the South African rand.
Even the international vehicle code for South Africa has been "ZA" since 1936.