Some example flows for a Medium post about how DNS works.
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October 16, 2018 09:16
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How DNS works
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| title Uncached DNS request | |
| participant "User agent" as user | |
| participant "ISP DNS" as edge | |
| participant "A" as com | |
| participant "B" as example.com | |
| participant "C" as bar.example.com | |
| participant "D" as foo.bar.example.com | |
| user -> +edge: Lookup foo.bar.example.com | |
| edge -> edge: Do I have a cache for foo.bar.example.com.? No | |
| edge -> edge: Do I have a cache for bar.example.com.? No | |
| edge -> edge: Do I have a cache for example.com.? No | |
| edge -> edge: Do I have a cache for com.? Yes | |
| note over edge,D: In reality, it will have at least 'com.'\nand in popular cases, `example.com.` | |
| edge -> +A: Lookup example.com. | |
| A --> -edge: Records for example.com. | |
| edge -> edge: Follow NS record to Name Server B | |
| edge -> +B: Lookup bar.example.com. | |
| B --> -edge: Records for bar.example.com. | |
| edge -> edge: Follow NS record to Name Server C | |
| edge -> +C: Lookup foo.bar.example.com | |
| C --> -edge: Records for foo.bar.example.com. | |
| edge --> -user: Records for foo.bar.example.com |
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