The transport ayer protocols used for real time multimedia, file transfer, DNS and email, respectively are
(A) TCP, UDP, UDP and TCP
(B) UDP, TCP, TCP and UDP
(C) UDP, TCP, UDP and TCP
(D) TCP, UDP, TCP and UDP
Ans: (C)
Explanation :
TCP is a connection oriented, reliable protocol and UDP is a connection-less, unreliable protocol.
Realtime multimedia (e.g., youtube) stream is implemented using UDP protocol because it is occassinally fine to get a noise (few pixels disturbed) but it is irritating to wait for the next screen to appear (if implemented on a realiable connection oriented architecture).
File transfers need TCP protocol, because file transfer is expected to copy each and every bit of the original file. That is why FTP (File Transfer Protocol) depends on TCP at the transport layer.
DNS (Domain naming system) is used to easily translate memorized domain names to numerical IP addresses needed for the purpose of locating computer services and devices worldwide. It is implemented on top of UDP. If there is error, the clients basically retry.
Emails : Emails are sent through application layer called SMTP (Simple Mail Transfer Protocol) which is implemented on top of TCP, because it is not acceptable to send some text of the e-mail garbeled.
Concepts to revise :
OSI Model
TCP/IP Protocol
Different layers in these models.
References :
(A) TCP, UDP, UDP and TCP
(B) UDP, TCP, TCP and UDP
(C) UDP, TCP, UDP and TCP
(D) TCP, UDP, TCP and UDP
Ans: (C)
Explanation :
TCP is a connection oriented, reliable protocol and UDP is a connection-less, unreliable protocol.
Realtime multimedia (e.g., youtube) stream is implemented using UDP protocol because it is occassinally fine to get a noise (few pixels disturbed) but it is irritating to wait for the next screen to appear (if implemented on a realiable connection oriented architecture).
File transfers need TCP protocol, because file transfer is expected to copy each and every bit of the original file. That is why FTP (File Transfer Protocol) depends on TCP at the transport layer.
DNS (Domain naming system) is used to easily translate memorized domain names to numerical IP addresses needed for the purpose of locating computer services and devices worldwide. It is implemented on top of UDP. If there is error, the clients basically retry.
Emails : Emails are sent through application layer called SMTP (Simple Mail Transfer Protocol) which is implemented on top of TCP, because it is not acceptable to send some text of the e-mail garbeled.
Concepts to revise :
OSI Model
TCP/IP Protocol
Different layers in these models.
References :
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