Domain Name System (DNS) is a critical component of every website or eCommerce store. If DNS doesn’t perform, a site can’t be fast. If a site is slow or unavailable, DNS is a likely candidate. In this article, we explain what DNS is, how it can affect your site, and how you can test DNS to make sure it’s working correctly.
DNS is responsible for transforming a domain name like nexcess.net into an IP address that computer networks understand. When a user clicks on a link or enters a URL in their browser, the browser asks a domain name server if it knows the associated IP address. The domain name server is usually hosted by the user’s ISP, although there are public domain name servers hosted by organizations like Google and Cloudflare.
If the domain name server knows the IP address, it tells the browser. If it doesn’t know, it asks another domain name server, which might ask another server, and so on until the answer is found. The order in which servers are asked is determined by a hierarchy. In the case of nexcess.net, the root domain server is asked which DNS server knows about the .net top-level domain, and that server is asked about the nexcess.net domain. All of this is complicated by geographic redundancy: duplicates of major DNS servers exist all over the world.
Is DNS Slowing Your Site Down?
DNS lookups should be a small proportion of your site’s total load time. The browser does nothing while it’s waiting for a response to a DNS request. If you’ve ever clicked on a link and wondered why your browser seems to be stuck, it’s because it is waiting for a response from a DNS server.
Ideally, DNS lookups should take less than 100 milliseconds from any part of the world from which a site gets substantial traffic. A web performance tool like Pingdom can tell you how long each lookup takes from locations around the world. There are several possible causes for slow DNS lookups. If the lookups are slow for you, but fast from elsewhere in the world, the issue is with your ISP’s DNS servers. If lookups are slow from everywhere, then the problem is most likely a slow DNS host. The solution is to host your domain records with a fast global DNS hosting provider.
Have Your DNS Records Propagated?
DNS is a hierarchical and geographically distributed system with many thousands of individual servers spread across the globe. When a site owner edits the DNS records of their site’s domain, the new records have to be synchronized with servers around the world — a process called DNS propagation.
Propagation isn’t instantaneous; it can take up to 24 hours for domain records to propagate. Until they do, some DNS servers will respond to requests with the old records. In some cases, a DNS server might not be able to find any records at all. In consequence, when the site owner or a user tries to visit the site, they may not get the expected results.
This can be confusing and frustrating for web hosting clients who want their domain to work immediately, but propagation takes time. Hostdedi developed a tool to help hosting clients figure out how far DNS propagation has progressed for their domain. Enter your domain, and the tool will tell you which DNS servers around the world have your DNS records.