CNAME instead of A-record: seo problem?

[Olaf]

Our supplier of a hosted CMS is hosting a few hundred website on his server. For every domainname pointing to a website we need to use the same IP-adres in the DNS A-record. They are now asking us to delete de A-record for all the websites and add a CNAME record. So they can send the traffic via a company like Versign in case of a DDOS attack.

A lot of the websites rank well. Will there be a SEO problem when we start using the CNAME's instead of the A-records?

Thanks, Olaf

[wissamdandan]

Am pretty sure, There will be no problems if you are using either of them.

Search engines will never know if you were using A- or a CName record.

On quick check you need to know, is to have the company make sure that the search engines are not accessible to your content on their host (duplicate). (better to use HTTP auth)

[Olaf]

"Search engines will never know if you were using A- or a CName record"

But if the Google bot's asks for a domainname and they will receive a domainname (the CNAME domain) they can understand it's a CNAME. Otherwise they would receive an IP-adres.

[wissamdandan]

Olaf,

I dont think i understood your reply,

how he asks for a domain name?

your cname will be for example abc.olaf.com

[Olaf]

Thanks for helping Do you mean that everything is happening on the DNS server and that Google/ requester/ browser won't see the proces from CNAME to A-record- to IP-address.

What I mean is:

1. Is the DNS server fully resolving the request at once (from CNAME to A-record to Ip-adres) or

2. is it a two step proces (lookup from CNAME to A-record, then another lookup from A-record to Ip-address by the requester).

In case 2 the requester can see that it's a CNAME construction because there are two steps.

[wissamdandan]

If i m not mistaken #1 will apply. it will fully resolve