Easy DNS mistake with TXT and wildcard records

I recently discovered that it's actually quite easy to get your DNs settings wrong and potentially take your site offline. Especially if you've got a lot of domains and subdomains. This issue is specifically to do with having a wildcard set up for your domain and also having TXT records for subdomains.
I thought I'd better share this to stop any one else making the same mistakes I have.

Best Domain Registrars

We have a lot of domains registered for work and we often need to have good control over the zone records. Unfortunately not all registrars make this easy for you. So I thought I'd do a comparison of some of the ones we use or have used to help decide where to keep all of our domains.

In this comparison I've included the following sites:

• GoDaddy
• Daily
• UKFast
• 123-reg
• Easily
• NetBenefit
• NetNames
• Network Solutions

I've used all of these except UKFast. But where I couldn't test the interface myself I just asked their support team.
Here's the data table: