2022
ByteByteGo - What is OSI Model | Real World Examples of 4:44
    https://www.youtube.com/watch?v=0y6FtKsg6J4
2019
Izotov - TCP/IT and shy this is needed for testers ru 20:00 of 1:35:58
    https://www.youtube.com/watch?v=rLUzYeLdM0k
    ! good, for dummies
2016
Romenskiy - Simple Calculation Method for IPv4 Networks and Masks ru of 47:16
    https://www.youtube.com/watch?v=AL4Ylbnw6hY
2014
Ashik - Nets and Protos ru of 1:48:31
    https://www.youtube.com/watch?v=LTZ8BVGRhH0