A domain name, for all practical purposes, is simply a website address. A domain name usually consists of a top-level domain (e.g., .com, .net, .org) and a second-level domain (the name you choose when you register the domain). In the case of vFlyer, for example, "vflyer.com" is the domain name, with ".com" as the top-level domain and "vflyer" the second-level domain. Domain names allow people like you and me to more easily navigate the Web.
DNS stands for "Domain Name System," and it's basically a gigantic database of the Internet. We use DNS to refer to "name servers" or "DNS servers," which are the bridge between a domain name and the IP address of the server hosting the destination website.
When you register a domain name, unless you specify otherwise, it is automatically assigned the DNS servers of the domain host (e.g., GoDaddy or Network Solutions). When you build a website and want to point your domain name to that site, changing the DNS servers to those of the service hosting the website is what links the domain name to the site.
If you publish a website with vFlyer Sites and want to point an existing domain name to it, updating the domain's DNS servers to DNS0.VFLYER.COM and DNS1.VFLYER.COM will accomplish this. You're essentially transferring control of the domain name from the previous domain host to vFlyer; if you don't want vFlyer controlling the domain name, then we recommend changing the A record of the domain name instead.
The "A" is short for Address, and the A record links a domain name to a static IP address. A records are also called host records.
When you update the A record of your domain name to @ A 220.127.116.11, what you're doing is pointing the domain name to your vFlyer Sites website (hosted at vFlyer's static IP address). Unlike changing the domain's DNS servers, changing the A record will just tell the domain host to point Web traffic to the specified website. It won't transfer control of the domain name to vFlyer, as changing the DNS servers would.
Times can range, but often it takes about 24 hours from when you make the DNS or A record change to when your domain name takes people to your new website.
If you already use an email hosting service for the domain name, the easiest thing to do is update the A record of the domain name to @ A 18.104.22.168 and leave the other domain settings intact. If you want to update the DNS servers to vFlyer's but still handle email separately, please email email@example.com with the MX records of your email service and we will make the necessary updates.