301 Redirect Best Practices - multiple sites to single site

Question

I have around 15+ sites, and we want to drop these sites and merge them into only one site (create pages for each one in the new site).

The 15+ site's domains should be redirected to one site as below:

a.com -> z.com/a
b.com -> z.com/b
c.com -> z.com/c
.. 

Also, we want to redirect (301) page by page from the old domains to the new the new domain to keep the page's ranking:

 a.com/about-us     -> z.com/a/about-us
 b.com/about/abouus -> z.com/b/about-s
 c.com/contactus    -> z.com/c/contact-us

Each one of the 15+ sites is running on its own server with a different platform while the new server is IIS.

Currently, I'm thinking of two approaches:

1. Point the old DNS records to the new server of z.com, and handle all the redirects on the server.
   

2. Keep the old site running, and configure redirect rules on each server to redirect each page to the matching page on the new site.

Which approach is better, any other approaches? So far I think the first approach is better since we will control all the redirects in one place - but from the performance wise, is it going to add more headache on the server?

Answer 1

I think eventually you'll have to shutdown all the other sites as in the long term unlikely does it make sense to keep 15 sites running just to do the redirects.

So as I understand the question is rather on how to better organize the migration to the new system in the short term. So here are my thoughts on this:

how huge is your system

• what's your QPS?
• how many pages do you have across your sites farm?
• do you need to remap URLS for a decent amount of pages?
• what's the migration procedure? Will you switch your sites one-by-one or it's technically infeasible and they all need to be swtiched over at once?

If we're talking about a system handling 10 QPS and 1K pages or about a system handling 50K QPS and having 1B pages we need to dynamically remap system load may be a concern and p.2 may look better

rollbacks

note that DNS records can be cached by intermediate servers and if you need to quickly rollback to the previous version if something goes wrong it can be an issue

what kind of systems do you have

Is it actually possible to easily extract URLs from 15 diverse systems and put them to a single point without a risk to lose something valuable?

ease of maintenance

At first glance the first approach looks easier from the maintenance perspective, but I don't know what kind of system you use and how complex the redirection rules need to be. If they are complex dynamic ones like a.com/product.php?id=1 => z.com/a/iPhone6S moving millions of such urls to a single point could be tricky

SEO

I don't follow the industry closely, but a few years ago both would work ok. I think it's worth consulting those keeping up to date with this industry - it changes very rapidly

Answer 2

The Scenario

You created a new site and you want to redirect all old sites(15+) to new site (page to page).

All old sites are running in it's own server on different platforms whereas the new one is IIS.

Your options

1. Point the old DNS records to the new server of z.com, and handle all the redirects on the server.

Advantage

---

• Less cost - you can remove all old sites and the server cost can be saved.
• Internal redirection. So, time will be less

Disadvantage

---

• Complex to perform
• take care of conflict of similar pages(double check the redirection path)

---

2. Keep the old site running, and configure redirect rules on each server to redirect each page to the matching page on the new site

If you can afford the cost of running 15 different sites on 15 servers just to redirect, then only go for this method.

It is just a waste of money and the redirection time will be more.