We have a PN Business fibre account, and have had our (ourcompany).co.uk domain and DNS records with PlusNet for years - with zero problems and good support when we have needed it.
Unfortunately our webhosting company want to move the site to Cloudflare, which requires DNS features not available with PlusNet (the webhosting say that we need our DNS records to be with a provider who can: a) Use CNAME for the apex record or b) Forward the apex to another domain (e.g. example.com -> www.example.com), or who can c) use a technique called CNAME flattening. They are explaining it badly, hence our confusion also.
So, we are looking at other places to register our domain and DNS records with, e.g. easyDNS.com
Obviously we need to make sure that other services e.g. email are not affected by the move - our DNS at present looks like this (redacted):
mail - A - 221.108.x.58 (our SBS/Exchange server) remote - A - 221.108.x.58 (our SBS/Exchange server) www - A - 143.223.x.112 (our website host pre-Cloudflare move) ourcompany.co.uk - A - 143.223.x.112 (our website host pre-Cloudflare move)
MX - ourcompany.p10.spamcheck.com (we send our email direct from our own Exchange Server on-premise, but incoming email is first received and checked by a Spamcheck service, before they then forward to our on-premise Exchange Server)
On the exchange server, we setup to relay mail through the smart host "relay.plus.net". Mail is addressed as in: firstname.lastname@example.org
All of this has worked reliably for ages, so it would be a PITA if moving domain registrar and DNS record holder from PlusNet would cause any issues - any ideas?