Web / Traefik Interview questions
What is the difference between HTTP-01 and DNS-01 challenge types in Let's Encrypt?
Both are ways Traefik proves domain ownership to Let's Encrypt before it will issue a certificate, but they verify that ownership differently.
| HTTP-01 | DNS-01 |
| Proves ownership by serving a file on port 80 | Proves ownership by creating a DNS TXT record |
| Requires the domain to be publicly reachable on port 80 | Works even for internal or non-public services |
| Cannot issue wildcard certificates | Can issue wildcard certificates (e.g. *.example.com) |
| No DNS provider API integration needed | Requires a supported DNS provider and API credentials |
Teams that need wildcard certificates, or that run services not reachable on port 80 from the internet, use DNS-01, while HTTP-01 remains the simpler default for publicly reachable single-domain services.
Which challenge type is required to issue a wildcard certificate?
HTTP-01 challenge validation requires:
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