Round Robin records are records with the same name value that point to different IP addresses or different Fully Qualified Domain Names. For instance, you can have the domain domainexample.com pointing to the IPs 1.1.1.1 and 2.2.2.2 simultaneously. This means that, if you query the domain domainexample.com, there is a 50% chance that the host 1.1.1.1 will respond to that request.
Let's use user.domain.com as an example. Below you can see that the A record for the user.domain.com points to three different IP addresses.
Record Name | Record Type | Record point to IP |
user.domain.com | A | IP #1 |
user.domain.com | A | IP #2 |
user.domain.com | A | IP #3 |
Now we have three users that are visiting the domain user.domain.com. When user one asks for the domain, they will be pointed to, for instance, IP #1. The second user will be served with the domain content by IP #2 and so on. This is a rotation process, considering that the IPs have been configured to receive traffic equally for that specific record and taking into account that the record is not cached in any of the user's systems.