Nameservers

Nameservers are the servers that answer every DNS question about your domain. If none of them answers, your website, your mail and everything else that depends on the name stops working, even though the servers behind them are healthy.

What to aim for

• •At least two nameservers, as the standard requires. Four is common at managed providers.
• •Servers on different networks, so one outage or one routing problem does not take all of them down.
• •Records that agree. Every nameserver should return the same answers, and the delegation at your registrar should list the same set that your zone does.
• •Consider a second provider for important domains. An outage at your DNS provider is then survivable.

Common failure modes

• •A single nameserver, or two names that resolve to the same address.
• •A lame delegation: the registrar lists a server that no longer answers for the domain, usually after a provider change.
• •Nameservers that disagree after a migration because only one was updated.
• •A registrar account with weak protection. Whoever controls the delegation controls the domain, so use a strong password, two-factor sign-in and a registrar lock.