My present DNS configuration for my website's A record is as below
In above configuration user can open website either by example.com or by www.example.com.
One of my SEO team-member argues for single point access.
According to him search engine’s crawler see 2 different name with same content. It is not good and we should configure domain in such a way that if user open example.com then browser automatically get redirected to www.example.com.
You don't need to change DNS for this at all.. He is correct in his argument though. Google doesn't like the same content for multiple hosts. So pick which one you want to use
example.com or www.example.com and do a 301 redirect from the one you don't want to use to the one you want to use.
The 301 re-direct is done with your webserver not dns. The 301 tells google.. hey.. the site now lives here.. change your links to use this url now and not the old one if it has links to both of the hosts.