Is a 302 temporary redirect to a 503 maintenance page (on another domain) acceptable for SEO during site maintenance?

Question

I'm working under an IIS environment. I would like to put up a splash page for our site maintenance, however, the splash page (app_offline.htm) has to be served on a separate site, since our developers still want to be working with the site while the app_offline.htm is up.

My plan: Use URL-Rewrite to separate traffic to two groups by IP, Public and developers. For developers, "None" action is applied, for public, they will be redirected to an app_offline.htm (503) page on a separate server.

Since it is a redirect to app_offline.htm. I'm assuming when Google robots will first pick up a 302, then pick up a 508?

Eventually does the 503 count or does only the 302 count?

I figured I had to put app_offline on another site since it brings down the entire site and beats the purpose of separating the IPs. But any better alternative to my plan will be appreciated too.

Answer 1

Redirecting to a maintenance page during a short maintenance window should not cause Google any problems compared to showing a maintenance page directly.

Because so many sites configure redirects to error pages of all types (especially 404), Googlebot has to know how to deal with that situation.

In general, Google is fairly forgiving about maintenance windows. They won't drop your site from the index even if the entire thing is serving up 404 pages for less than a day. The only status code that causes them to drop pages from the index quickly is the "410 Gone" status.