Wikipedia
.ad
.ad is the Internet country code top-level domain ( ccTLD) for Andorra. It is administered by Servei de Telecomunicacions d'Andorra, today called Andorra Telecom.
Because ad is also an abbreviation for the word advertisement or advert, .ad has also been used in an unconventional manner as a domain hack by some advertising media companies and also the year usage of 20XX.ad.