DNS is core in the construction of all online services. Websites, emails, business systems, IP telephony, apps, etc. are all dependent on DNS working. That’s why DNS service outages can create a lot of problems for businesses, the consequences being lost revenue, reduced productivity, and damaged brand trust.
One reason why they stop working could be that the provider has poor security, such as a lack of redundancy or a vulnerability to attacks. Or it could simply be due to a lack of control over where you have your DNS services and who is responsible for them. This is something that many discover too late. That’s why it is vital to find the right provider.