How to Setup Canonical Domain Names with Apache

“Using canonical URLs you can merge all of these so that your
web server treats them all the same in a web browser. This has a
positive impact on search engine optimization. Not using canonical
URLs has a negative impact on your SEO, as Google notices that
several URLs are returning the same content and penalizes you.

“Canonical domain name is the full form of CNAME. You might have
encountered this term while setting up your domain name. CNAME is
an entry, which is a part of your domain’s DNS records. A computer
hosting a website has an IP address, which is used to access the
content over the web. DNS helps us avoid distributing numeric IP
addresses to people and handles the conversion from domain names to
IP addresses. This is pretty straightforward when you have one
website being served by an IP address. However, you might want to
serve various websites with the same IP address and the same domain
name. This can be done using subdomains such as forums.sevenacross.
The subdomains are handled by the domain’s CNAME records.”

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