Computer Network

Updated: 2018-12-22

TCP/IP Model(4 Layers)


  • Application: HTTP, FTP, telnet
  • Transport: TCP, UDP
  • Network: IP, ICMP
  • Link: device driver

OSI Model(7 Layers)


  • Layer 7: Application Layer: HTTP, FTP
  • Layer 6: Presentation Layer
  • Layer 5: Session Layer: controls the dialogues (connections) between computers.
  • Layer 4: Transport Layer: TCP, UDP
  • Layer 3: Network Layer
  • Layer 2: Data Link Layer

    • Media Access Control (MAC) layer
    • Logical Link Control (LLC) layer
    • Point-to-Point Protocol (PPP)
  • Layer 1: Physical Layer

Important Protocols

A few protocols that a software engineer may care or interact with:


Anycast addressing uses a one-to-nearest association; datagrams are routed to a single member of a group of potential receivers that are all identified by the same destination address.

what happens: type in browser, use Anycast to find the nameserver(google/godaddy), nameserver lookup your ip in their records, the request is redirected to that ip, your server receives the request, parse the http request, retrieve static html or data from databse, return response, user’s browser receive response, render HTML


Multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource.

Domain Names

FQDN: Fully Qualified Domain Name: sometimes also referred as an absolute domain name is a domain name that specifies its exact location in the tree hierarchy of the Domain Name System(DNS)

TLD: Top Level Domains