Changes to Authoritative nameservers make many people uneasy. They may worry about service disruptions and downtime. Sometimes as a result of previous experience. Sometimes as a result of a change to an individual DNS entry on the current Nameserver. This article serves to address those concerns.
Disruptions happen when traffic can’t reach its destination. Or if details are not matching.
If you’ve experienced a service disruption in the past related to a Nameserver change, it’s was likely due to one (or more) of these reasons:
- A. The DNS entries on the new Nameserver were incomplete or not an exact match in both locations.
- B. The old Nameserver’s DNS records were removed before 48 hours had passed and propagation had completed.
- C. One of the Nameservers went offline for some period of time.
If the DNS records at "New Nameserver" are an identical match with the DNS records at "Old Nameserver", then requests will be correctly routed regardless of whether they’ve passed through "Old Nameserver" or "New nameserver".
It may take the entire Internet up to 48 hours to be informed that "New Nameserver" has been designated as authorative. Until that 48 hours has passed some requests may still pass through "Old Nameserver" but the traffic will get through to it’s intended destination either way.
Downtime during a Nameserver switch
Traffic flows either through "Old Nameserver" or through "New Nameserver" similiar to how a light switch is either on or it is off.
The time in between the two states (if measured) would likely be in the billionths or trillionths of a second. For this reason we can say that basically there is zero time in-between states.
Allow up to 24 hours for this change to be processed. There will be no downtime when you switch your name servers. Traffic will gracefully roll from your old name servers to the new name servers without interruption. Your site will remain available throughout the switch.
It may take up to 24 hours after successfully changing name servers for a new SSL certificate pack to be issued for your site. If you need valid SSL certificates in place before sending traffic through Cloudflare, pause Cloudflare for your site by clicking on Advanced to the right and resume when your certificate pack has been issued. - Cloudflare
Imagine a car on a 2 lane highway into a city. Both lanes of the highway are going to the same destination.
- As the car changes lanes the city does not momentarily disappear. Not even for a blink of eye. The destination is always there even when the car is in the middle of the painted lane divider.
- As the car changes lanes there was no period where it was not moving toward the city.
Now if the new lane had a giant crater in it, the car would definately have a problem. But since the driver visually checked the new lane for craters before putting on the turn signal, the driver can proceed safely.
- The driver does not need to wait until 8pm to change lanes.
- The driver does not need to wait until the weekend to change lanes.
Skunkworks has succesfully migrated Nameservers without any downtime from the following providers in the past.
- and others
Remember: Mail servers will also re-try on connect/DNS failure so you aren’t likely to miss any emails during some tiny window.