TCP/IP & Web · solulu

TCP/IP Reference Model

It is a compressed version of the OSI model with only 4 layers. It was developed by the US Department of Defence (DoD) in the 1860s. The name of this model is based on 2 standard protocols used i.e. TCP (Transmission Control Protocol) and IP (Internet Protocol).

Link : Decides which links such as serial lines or classic Ethernet must be used to meet the needs of the connectionless internet layer. Ex - Sonet, Ethernet
Internet : The internet layer is the most important layer which holds the whole architecture together. It delivers the IP packets where they are supposed to be delivered. Ex - IP, ICMP.
Transport : Its functionality is almost the same as the OSI transport layer. It enables peer entities on the network to carry on a conversation. Ex - TCP, UDP (User Datagram Protocol)
Application : It contains all the higher-level protocols. Ex - HTTP, SMTP, RTP, DNS.

HTTP and HTTPS

HTTP is the HyperText Transfer Protocol which defines the set of rules and standards on how the information can be transmitted on the World Wide Web (WWW). It helps the web browsers and web servers for communication. It is a ‘stateless protocol’ where each command is independent with respect to the previous command. HTTP is an application layer protocol built upon the TCP. It uses port 80 by default.

HTTPS is the HyperText Transfer Protocol Secure or Secure HTTP. It is an advanced and secured version of HTTP. On top of HTTP, SSL/TLS protocol is used to provide security. It enables secure transactions by encrypting the communication and also helps identify network servers securely. It uses port 443 by default.

DNS (Domain Name System)

DNS is an acronym that stands for Domain Name System. DNS was introduced by Paul Mockapetris and Jon Postel in 1983.

It is a naming system for all the resources over the internet which includes physical nodes and applications. It is used to locate resources easily over a network.
DNS is an internet which maps the domain names to their associated IP addresses.
Without DNS, users must know the IP address of the web page that you wanted to access.
Working of DNS: If you want to visit the website of “shaurya”, then the user will type “https://www.shaurya.com” into the address bar of the web browser. Once the domain name is entered, then the domain name system will translate the domain name into the IP address which can be easily interpreted by the computer. Using the IP address, the computer can locate the web page requested by the user.
DNS Forwarder : A forwarder is used with a DNS server when it receives DNS queries that cannot be resolved quickly. So it forwards those requests to external DNS servers for resolution.

SMTP Protocol

SMTP is the Simple Mail Transfer Protocol. SMTP sets the rule for communication between servers. This set of rules helps the software to transmit emails over the internet. It supports both End-to-End and Store-and-Forward methods. It is in always-listening mode on port 25.

TCP vs UDP

A key difference between TCP and UDP is speed, as TCP is comparatively slower than UDP.

TCP is a connection-oriented protocol, whereas UDP is a connectionless protocol.
Overall, UDP is a much faster, simpler, and efficient protocol, however, retransmission of lost data packets is only possible with TCP
TCP provides extensive error checking mechanisms. It is because it provides flow control and acknowledgment of data. UDP has only the basic error checking mechanism using checksums.