Checklist to Transfer Your Domain with Zero Downtime
Before you start
Review the contact information Transfers extend the domain expiration date by 1 year SSL certificates are not affected TLDs, like .CO.UK follow a different set of rules Transfers can take up to 5 days to complete
Step 1: Transfer the DNS
If the DNS for your domain is with your current registrar, you'll need to transfer the DNS first. This step allows your site and email to keep responding while the domain is transferring.
Create DNS Name Server (Bestpass) Import the DNS records at your new provider(Bestpass). Change the name servers at your current registrar.(SPAN)
Step 2: Transfer the domain
If the DNS for your domain is not managed by your current registrar, there will be no downtime while you transfer the domain.
Unlock the domain at your current registrar. Request the authorization code. Start the transfer at the new registrar. Approve transfer authorization email. If the loosing registrar allows immediate for transfer approval, you'll receive an email to approve the transfer at the new registrar. If not, you'll need to wait up to 5 days before the transfer auto completes. Verify that your domain was transferred. 
