Some important concepts
- DNS: Domain Name System, translates human readable domain names (for example, www.Azure.com) to machine readable IP addresses (for example, 20.43.132.131)
- Some top level domain examples:
- .com
- .gov
- .gov.uk
- .co.in
- .com.au
- Some domain registrars:
- Amazon
- GoDaddy
- 123-reg.co.uk
- Start of Authority (SOA) : SOA is a set of data that provides critical resources for the Domain Name System that helps to validate domains on the Internet. It contains information of
- Administrator
- Server
- time-to-live etc.
- NS Record: Name Server Record tells the Internet where to go to find out a domain's IP address. A domain often has multiple NS records which can indicate primary and secondary nameservers for that domain. Without properly configured NS records, users will be unable to load a website or application.
Example:
| example.com | record type: | value: | TTL |
|---|---|---|---|
| @ | NS | ns1.exampleserver.com | 21600 |
Note that NS record never points to CNAME record
- A Record: A record is fundamental record type provides the associated IP address for the domain name. Example: www.Azure.com --> 20.43.132.131
- TTL (Time-to-live): Either resolving server or local user machine cache IP info related to domain name for the TTL. So any change in IP for a domain takes the time mentioned in TTL to take effect on internet.
- Canonical Name Record (CNAME): CNAME is just used to point one name to another.
Example: example.com to www.example.com, ultimately it point same IP address. - Alias Record: It works same as CNAME to referencing other name. the difference is a CNAME can't be used for naked domain name.
Example: used for cloudfront, load balancers, S3 buckets those configured as websites.
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