I know that there are protocols called the TCP protocol and the UDP protocol and the IP protocol, but what is the protocol at the data link layer in Ethernet called? is it called the "MAC" protocol or the "Ethernet" protocol?
There are many data-link protocols. Some use MAC, and some do not. The IEEE data-link protocols use MAC. Some are ethernet, token ring, FDDI, Wi-Fi, etc.
There are also other data-link protocols that do not use MAC. PPP only has two endpoints, so it does not need MAC or addressing because any frame sent is destined to the only other host on the link. Others, such a frame relay, ATM, etc. use something else.
Ethernet is a series of both physical and data-link protocols that are collectively called ethernet. Wi-Fi is a series of physical and data-link protocols, collectively called Wi-Fi. Both use MAC, but they are different sets of protocols.
what is the protocol at the data link layer in Ethernet called?
While that is formally a protocol, it's more commonly just called "Ethernet data link layer", "Ethernet layer 2", or simply "L2".
is it called the "MAC" protocol or the "Ethernet" protocol?
Both terms are rather ambigous. "MAC" isn't only the addressing scheme shared across many IEEE (and even non-IEEE) data link layers, but also one of the two sublayers - MAC and LLC - used by those L2 protocols.
Since Ethernet defines both a data link layer protocol (with many options) and a large number of physical layer variants ranging from 1 to 400,000 Mbit/s, "Ethernet" could refer to any of those and is only used when the underlying details are of no interest.
I am writing some keys based on the notes I took from Cisco trainings. I note which definition is technology, which definition is connection, which definition is standard. Ethernet technology, Ethernet connection, LLC sublayer IEEE 802.2 standard, MAC sublayer IEEE 802.3 standard, MAC sublayer IEEE 802.11 standard,