CNAME for subdomains needed? [closed]

Question

Hay, I'm having a little trouble.

I have the following domain over at easily.co.uk

www.foo.com

and i have that site hosted over at 1and1. This site is working fine.

I want to add a subdomain to this site, so i went into Plesk and added the followig subdomain

bar.foo.com

However, when i point my browser to that subdomain, it fails.

Do i need to setup a CNAME record for this subdomain?