A 3xx response carries Retry-After. What does that field mean there?
The minimum time the user agent is asked to wait before issuing the redirected request✓Bonne réponse
How long the redirect itself remains valid before it must be re-fetched
Nothing; Retry-After is only defined for 503 and is ignored on 3xx
The maximum time the user agent may delay before the redirect target expires
Explication
Retry-After is defined for more than 503: with any 3xx it sets a minimum delay before the redirected request is issued. With 503 it instead estimates how long the service will be unavailable.