This is a nit-pick, but AWS is not now nor ever shall it be so big that it gets to redefine basic networking terminology. A lot of people taking this exam are learning the nomenclature of networking, and we ought teach them the right nomenclature.
"You have the app currently hosted in three regions around the globe and you have defined Route 53 Geolocation routing to route people to the nearest region. Some customers complain that they are not able to access the service. What could be the cause?"
DNS (Route 53 or otherwise) does not perform any routing. DNS provides answers on which basis the questioning host’s network stack may perform routing.
Thus, any answer referring to "route" is wrong. The answers should be:
You need to adjust the bias factor for the geolocation ANSWERS.
You need to ensure that you have a default ANSWER in addition to other geolocation ANSWERS.
You need to use a CNAME record rather than an A record.
You need to ensure the weights of all routes do not exceed 255. – COULD GO EITHER WAY; THIS COULD BE A RED HERRING, BUT IF NOT, "ROUTES" SHOULD BE "ANSWERS."
You need to use an AAAA record rather than an A record.
@Scott – do agree that AWS uses the term "route" with Rt53 (Actually even the service is called Route)