When URL with www does not resolve

I had set up my site url as sitedomain.com in route 53 with all the associated records. The site resolved fine when accessed via sitedomain.com, but did not resolve when accessed via www.sitedomain.com. In other words it did not resolve when adding the 'www' prefix to the URL. I tried setting up an entirely separate domain in route 53 which included the 'www' but that was also not correct.

The solution as provided was ->
'In order to get www.yourdomain.com working you need to create a CNAME record in your hosted zone pointing to yourdomain.com record'.

I'm sure there are google entries for this but I couldn't find any so thought I would share this in the hopes of helping anyone with a similar problem.