Which nameservers should I use?

When moving your domain back to AWS Route 53 from Cloudflare, you need to ensure that your nameserver configuration is consistent across all settings. Here's what you should do:

1. In domain settings: You should use the four Route 53 nameservers that are assigned to your hosted zone. These are unique for each hosted zone. To find these nameservers:

• Go to the Route 53 console
• Navigate to "Hosted zones"
• Select your hosted zone (radio button)
• Click "View details"
• Look under "Hosted zone details" for the four nameservers listed

2. In SOA record: You don't need to manually create or modify the SOA record. Route 53 automatically creates and manages the SOA record when you create a hosted zone. Do not create additional SOA records or delete the existing one.

3. In NS record: Similar to the SOA record, Route 53 automatically creates the NS record with the four nameservers assigned to your hosted zone. These should be the same nameservers you use in your domain settings. Do not create additional NS records or delete the existing ones.

It's critical that the nameservers listed in your domain registration settings match exactly with those in your Route 53 hosted zone. If there's a mismatch, you'll experience DNS issues like the inability to resolve records or problems with services that rely on DNS verification.

After updating the nameservers, allow up to 48 hours for DNS propagation to complete, though changes often take effect much sooner.
Sources
Making Route 53 the DNS service for an inactive domain - Amazon Route 53
Making Route 53 the DNS service for a domain that's in use - Amazon Route 53
SOA Record from Route57 register domain cannot be found by DNSchecker.org | AWS re:Post