Question, if you have a site, that you basically want to forward all traffic from, would you use a 301 redirect? I have lost all pages on a server except for the 404, so I am thinking about 301 redirects to the new site which is all new content. I know this is two questions and not very clear, but it was a long night of damage control...
Using a 301 redirect, you are directing your site from one location (server) to another. There is no such thing as a 404 error redirect - you can create a customized 404 page that people will be directed to if they are trying to locate a page that no longer exists. The error codes that start with 4 are called client errors
I guess my question was not well written. If someone reaches an error page that redirects them to the new home page (new site and new content), is this good or bad SEO.
Now I understand - but I really do not know. I am sure others would know of course. I have seen a lot of 404 custom pages that have site maps, etc on them (not that that makes it good).
I have just completely removed one site and moved to another office. I want anyone who reference any of the old pages to find the new site, with the new office...
Never had a problem with a permanent redirect over the long term myself, my top site in the se's uses it exclusively to send any bad requests to the main index.html unless I specfically send it elsewhere. Watch temp redirects though, those can hurt very bad.
If you use a 301 redirect for the site, no one should ever see the 404 page, since all requests for www.oldsite.com will take the visitor (or spider) to www.newsite.com. On the other hand, it if the actual page filenames have also changed, a custom 404 on the new site is a good idea. Mine includes a full navigation system and a search box -- see example here and feel free to beg, borrow, or steal anything except the images from that page.