# Let's Encrypt can reach an HTTP-01 challenge URL, but cert-manager's self-check can't because the network has no NAT loopback. Which cert-manager 1.21 solver option handles this?

cert-manager, Hard (Expert), Troubleshooting. https://k8wiz.com/uquiz/lets-encrypt-can-reach-an-http-01-challenge-url-but-cert-managers-self-check-cant-because-the-network-has-no-nat-loopback-which

- A. waitInsteadOfSelfCheck
- B. skipSelfCheck
- C. selfCheckTimeout
- D. disablePropagationCheck

**Answer:** waitInsteadOfSelfCheck

**Explanation:** Added in cert-manager 1.21, waitInsteadOfSelfCheck on an http01 or dns01 solver skips the self-check and waits the given duration after presenting the challenge before asking the ACME server to validate. It is meant for NAT loopback limits, split-horizon DNS and similar setups. A delay that is too short lets validation start before the solver is reachable.