Data Transfers · Downloads and large files
Do large downloads resume where they left off if they're interrupted?
Short answer: Yes. A single large file (about 2 GB or more) coming to your Mac is downloaded in pieces, so after an interruption it continues from where it stopped, then is checked when complete — if the service supports partial downloads.
Yes, for a single large file coming down to your Mac. Files of about 2 GB or more are fetched in pieces; if the connection drops, the Mac sleeps or you pause, everything already downloaded is kept and the transfer carries on from there. When all the pieces have arrived, they're put together and checked before the file is marked finished.
This needs a service or web server that can send part of a file. If it can't, the log says so — "This service can't send part of a file…" — and the file is sent in one pass.
Smaller files and whole folders don't need this: an interrupted folder transfer simply sends whatever isn't there yet when it runs again.