I have been doing a server migration, and checking that everything related to DNS is configured correctly by using IntoDNS. After doing this though, it flags up a error saying that there is no A record for WWW. The website is working fine, and I noticed that there is only a CNAME record for that subdomain.
My question is, should I have both a CNAME record and an A record for that subdomain, or is a CNAME sufficient and I can safely ignore that error? Could it potentially prevent access for someone using a client that doesn't implement CNAME?