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24 lines
1.7 KiB
24 lines
1.7 KiB
# Domain Name System |
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A Domain Name System (DNS) translates a domain name such as www.example.com to an IP address. |
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DNS is hierarchical, with a few authoritative servers at the top level. Your router or ISP provides information about which DNS server(s) to contact when doing a lookup. Lower level DNS servers cache mappings, which could become stale due to DNS propagation delays. DNS results can also be cached by your browser or OS for a certain period of time, determined by the time to live (TTL). |
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- NS record (name server) - Specifies the DNS servers for your domain/subdomain. |
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- MX record (mail exchange) - Specifies the mail servers for accepting messages. |
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- A record (address) - Points a name to an IP address. |
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- CNAME (canonical) - Points a name to another name or CNAME (example.com to www.example.com) or to an A record. |
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Services such as [CloudFlare](https://www.cloudflare.com/dns/) and [Route53](https://aws.amazon.com/route53/) provide managed DNS services. Some DNS services can route traffic through various methods: |
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- [Weighted Round Robin](https://www.jscape.com/blog/load-balancing-algorithms) |
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- Prevent traffic from going to servers under maintenance |
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- Balance between varying cluster sizes |
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- A/B testing |
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- [Latency Based](https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html#routing-policy-latency) |
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- [Geolocation Based](https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html#routing-policy-geo) |
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To learn more, visit the following links: |
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- [Getting started with Domain Name System](https://github.com/donnemartin/system-design-primer#domain-name-system) |
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[What is DNS?](https://www.cloudflare.com/learning/dns/what-is-dns/) |