Understanding DNS Concepts

In this, we will learn the DNS Concepts.

translates domain names into IP addresses
Needed as domain names are alphabetic and humans cannot remember IP address
Like www.example.com is translated to 198.105.232.4
DNS servers asks another DNS one if cannot translate a particular domain name
DNS service is implemented as hierarchical system of splitting domain name similar to a tree
Every node in tree is called domain and has a label
domain name of node is actually combination of all labels present on path from root to that node
Example for network.support.testprep.in
- support.testprep.in is the domain name.
- . is the root domain
- in is the top level domain
- testprep is the second-level domain
- support is a subdomain of microsoft
- network is the hostname
domain name space is partitioned into DNS zones
every DNS zone, start at node and go to leaf node or nodes where other zones start
DNS protocol use — port 53/tcp and port 53/udp.
DNS name resolution process has steps as
- local nameserver checks for authority on required domain name after getting query from client, if present IP address is replied or next step is taken
- root nameserver at next level down, is queried by local nameserver for IP address
- Querying is repeated till address is returned

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