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004 DNS Domain Name System (Goals for the design of DNS (Local…
004 DNS Domain Name System
A DNS takes a FQDM (Fully Qualified Domain Name) and map it to a corresponding IP address
Before DNS
Before DNS there was a host table, often called
host.txt
host.txt was a monolithic file mapping the names of all the ARPANET's hosts to their addresses
It was maintained by a single organization (SRI's Network Information Center), and
distributed by a single point (SRI-NIC)
Problems
Consistency/latency
Traffic and load on SRI-NIC
Collisions
Searching the file was lineal
Goals for the design of DNS
Local administration with global availability
Hierarchical namespace
What is the DNS?
It is the Internet's naming service
Responsible for mapping URLs into IP addresses and other data
DNS is also:
A distributed database
Partitioned into zones
managed in a distributed, decentralized way
Available globally, across the Internet
Database
DNS's indexes are dotted names (google.com), which are properly called
domain names
Domain names are actually
paths
in an inverted tree
Inverted tree