It isn't normally a 'class' system, it is often that new estates are either connected directly to the NBN by default or for ones which were commissioned before the NBN they will often have a dedicated RIM/TopHat or a form of 'sub-exchange' which have ports for that estate, and while sometimes it is possible to 'transpose' your connection to another RIM it isn't always possible...
ADSL becomes slower the further the line length is between you and the port, and if that length reaches 4KM anything longer and you are unlikely to get connected as that is when it starts to be unstable and excessively slower then expectations...
ADSL becomes slower the further the line length is between you and the port, and if that length reaches 4KM anything longer and you are unlikely to get connected as that is when it starts to be unstable and excessively slower then expectations...