DNS (Domain Name System) is the method that tells your web browser where a website is located.
When you own a domain name, your domain provider will allow you to manage your Nameservers and DNS. If you use your domain name providers default Nameservers then you will be able to modify your DNS records from there, if you use third party Nameservers then you will need to request that third party make changes if you need to modify your DNS.
Once you have established where to modify your DNS you will typically need to set a record for @ (or current origin/blank) and another for www.
The simplest way to do this is to use an A record which points at the IP address for your server. If you are unsure what your server IP address should be, your web host will be able to provide this for you. An example of this set up might be:
However we typically recommend using a CNAME for at least the primary record, usually www but you can check by visiting your website and seeing if it redirects to www.domain.com or just to domain.com. Using a CNAME for the www record might look like this:
Using a CNAME means that if the server changes IP address, the DNS lookup will still resolve correctly.
Please note: Unless you have set your TTL in advance, changing DNS records can take up 48 hours to resolve everywhere on the Internet. If you know in advance that you need to change your DNS you can often set the TTL to a low value, such as 1 minute, which will reduce any potential downtime.