What is identifier? In application layer, what are the types of messages? What are the needs for transport service? What are Internet transport protocols? Describe them? Give examples of applications that used them? What are application layer protocols? What are HTTP connections? Describe them? Describe in details (6 steps) what happens from client and the server sides when a user enters the following in his/her browser: www.apple.com Using non persistent HTTP protocol? Describe cookies? What is proxy server? What are its benefits? Describe FTP? Describe in details (6 steps) what happens when a user enters the following email from his/her mail client: To: Saqer@bbc.com Salam Omar Describe in details what happens when a client asks for IP of www.ku.edu? Kuwait university has a server with the hostname server1.kuniv.edu.kw with IP number 139.141.55.130. Assign an alias name www.kuniv.edu. Write The DNS database records (two records) for the above information