DNS (Domain Name System)

• Bridge the gap between humans and computers
  • Humans are better with names, computers are great with numbers
• Resolves names --> numbers
  • https://google.com --> 216.58.193.78
• Application Layer client-server system of computers and databases
• Made up of:
  • Name space
    • Entire collection of computer names and their IPs
    • Stored in databases on DNS name servers around the globe
  • Name servers
    • Hold databases organized in hierarchical structure
  • Resolvers
    • DNS client that requests info from DNS name servers

Root Servers

• Root of the DNS hierarchy
• 13 sets of root servers around the world
  • Operated by 12 different organizations
  • Each set has their own unique IP address

TLD Server

• Stores address information for top level domains (.com, .ca, etc.)

Authoritative Name Server

• Responsible for knowing everything about the domain
• Includes IP for the domain name

Domain Names

• Character-based names are easier to remember
• Last part of FQDN is called top-level domain (TLD)
• Can be registered with Internet naming authority
  • Works on behalf of ICANN
  • Restricts what types of hosts can be associated with .arpa, .mil, .int, .edu, and .gov
• Name resolution
  • Process of discovering IP address when you have the FQDN

Fully Qualified Domain Name

• Fully qualified domain names
• Unique character-based name

Computer Science Networking