What is DNS propagation?

For individual users, DNS propagation time depends on settings that are related to the internet service provider (ISP), time-to-live (TTL) settings, which dictate how long DNS servers save cached information, and the domain’s registry. When working at enterprise scale with an authoritative DNS provider, DNS propagation time depends on how fast the provider can propagate changes throughout its global infrastructure.

DNS, or the Domain Name System, plays a critical role in the management of domains and subdomains. DNS makes it possible for users to search domain names through web browsers (for example, www.example.com) rather than enter complex numerical IP addresses to access the website they are looking for. This process, which is known as DNS resolution, requires a series of DNS servers and DNS records that make the process seamless for users.

DNS records hold the information necessary to connect domain names with their corresponding IP addresses. DNS servers are interconnected, and when a change is made to a record in one server—like changing the IP address that is connected to a domain name—it takes time for the change to propagate across the other servers. If a user initiates a search and reaches a system where the change has not yet propagated, the user will receive an old address.

DNS record changes can take between a few hours and a few days to propagate across the internet. However, organizations can significantly shorten the propagation process—and cut propagation time to just a few seconds—by working with an authoritative DNS provider and developing a strong DNS management strategy.

DNS changes can occur for a wide variety of reasons, such as when a new IP address is connected to a domain name or when an organization chooses a new DNS provider. Updating A records, which create a direct connection between an IPv4 address and a domain name, creates a link between domain names and a new name server. Updating mail exchange or MX records, which direct emails to your domain mail server, impacts how emails are routed to a domain mail server. When any of these changes are made, they need to be propagated across DNS systems. The amount of time it takes for changes to be propagated depends on a few factors, and the process is different for individual users and enterprises.

When a user searches for a hostname by using an internet browser, it sets off a DNS query. This query performs a DNS look up to find the matching IP address. To speed up this process, you can set a time-to-live, or TTL, value that lets your DNS servers know how long they should cache information before refreshing the cache. Setting lower TTL values can help lower propagation times. It is also important to remember that different DNS record types vary in propagation speed based on their function.

The first step of this process is to pass the request to a DNS server known as a DNS recursive resolver, sometimes called a recursor or DNS resolver. Internet service providers usually set up these servers, which include local DNS caches that save DNS information for faster DNS lookups. The issue with ISPs is that they occasionally ignore TTL settings and save cached information for an extended period, which can lead to longer propagation times.

Changing a domain’s corresponding IP address impacts your authoritative DNS name server. The authoritative DNS server holds the final record on which IP address is connected to a specific domain. However, because DNS works on four interconnected servers, changes made to the authoritative name server must also pass through the other servers. These servers include the root server, which receives requests from DNS resolver servers, and the top-level domain (TLD) name server, which contains data that is related to domain names with the same extension. Making these changes across multiple server types can also slow down propagation.

On an enterprise level, organizations can use DNS solutions like IBM® NS1 Connect to avoid such propagation delays. For example, the NS1 platform provides near-instant propagation, meaning that any DNS changes are propagated worldwide in just a few seconds. The NS1 platform also allows organizations to set a low TTL and allows DNS clients to “hit” its DNS servers as often as needed, helping solve the problem of slow propagation.

There is no perfect way to monitor your global DNS propagation because it would be incredibly difficult to monitor the countless number of DNS servers located around the world. However, tools such as DNS propagation checkers can provide insight into propagation times. These solutions work by checking new domain DNS records on a sample of global DNS servers to see if propagation occurred. While not perfect, these insights can help organizations plan for DNS changes and reduce downtime.

To avoid such estimations, organizations can use an authoritative DNS provider that helps ensure DNS changes are quickly propagated worldwide.