Package Updates from a Local Server Fail to Download

Multiple Choice

Package updates from a local server fail to download. However, the same updates work when a much slower external repository is used. Why are local updates failing?

A) The server is running out of disk space.
B) The Internet connection is too slow.
C) The Internet is down at the moment, which causes the local server to not be able to respond.
D) The update utility is trying to use a proxy to access the internal resource.