TCP is connection oriented once connection is established data can be sent bidirectional Udp is simpler connection less internet protocol DNS(Domain Name Server's) are the internet's equal to the phone book.they maintain the directory of Domain names and translate them to internet protocol addresses​ this is necessary because , although Domain names are easy for people to remember computers or machines access website based on ip address Routers are small electronic devices that join multiple computer networks together via wired or wireless connections