Do I need to update shipping modules for end-of-year shipping rate updates?

Was curious about shipping setups. I saw another post that UPS and USPS shipping is built in to ZC. I know from playing around with my installed site that UPS rate estimator seemed to return shipping values, but my question is this:

Does ZenCart actually hit the rate servers of these two carriers to determine shipping, or how are rates kept current?

I know from having worked with commercial (and expensive) shipping systems in the past, that we would have to download update files to install on our shipping servers at the end of the year in order to maintain current book rates. This was especially true with UPS.

What about the UPS XML module contribution? Right now, I'd just be interested in UPS, FedEx, and USPS, but am not sure where to start.

Thanks for any info you could provide.

Does ZenCart actually hit the rate servers of these two carriers to determine shipping, or how are rates kept current?
Yes this is how it is handled and why at times when their servers are slammed it can cause issues....
As to how you need accounts with each and their sites are the best place for this