refrences book:

• Computer Networking: A Top-Down Approach. 7th edition

• Computer Networking: A Top-Down Approach. 7th edition, solution

• A Brain-Friendly Guide eBook: Al Anderson, Ryan Benedetti.

• data communications networking

• TCP/IP illustrated,volume 1

• TCP/IP illustrated,volume 2

• TCP/IP illustrated,volume 3

sites:

• CCNA Certification and Training Program