Pages that fail once

What this tests. Every fourth item answers 503 the first time you ask, then works. One page always fails.

The rule. Items 4, 8, 12 and so on answer 503 with Retry-After: 1 the first time your IP address asks for them. Ask again and you get the page. The site remembers you for 60 seconds; leave an item alone that long and it fails once more, so a fresh run sees the same failures. A scraper that retries gets all 20; one that doesn't gets 15.

And one page always answers 500. Retrying won't help; report it and move on.

• Medium
• HTTP only
• Answer key /bad/flaky/answers.json