How Long Does It Take for DNS to Update?
As we’ve talked about before, DNS is a global online protocol and one of the core technologies through which the internet functions. Working through multiple tiers of servers, it allows for the translation of domain names into IP addresses. In other words, it allows computers to understand requests made in human-readable language.
This process is usually lightning-fast, but there are certain aspects that can still take some time. One of these is DNS propagation, which can take anywhere from a few hours to three days to be completed. In this article, we’ll explore what exactly DNS propagation is, and why it can potentially take a while to be fully completed.
What Is DNS Propagation?
DNS propagation, or DNS updating, refers to the period of time between making a change to your domain name and seeing that change reflected in DNS across the internet. Propagation occurs after a few different types of actions, including making a change to your DNS records, or changing your domain name’s WHOIS information.
Making a Change to Your DNS Records
As mentioned above, DNS is a system that allows for the translation of domain names to IP addresses. Information about which domain name corresponds to which IP address is held inside DNS in a type of software called a nameserver. Nameservers act as a sort of library catalog, allowing for quick matching and retrieval of the information your web browser needs to complete a web search.
In other words, if you have a website, then your website’s information is stored in DNS. So, why would you make a change in your DNS records? This could be necessary for many reasons, including any changes made to your domain name or your web hosting provider.
Look at it this way: if the information a person enters when searching for your website doesn’t match the information stored in a nameserver, they won’t be able to find or access your website. The procedure for making a change in your DNS records will depend on your web hosting provider. Once a change has been made, it can take a while for that change to be reflected throughout the entire DNS network globally. We’ll discuss this more in a bit.
Making a Change in WHOIS
WHOIS is a widespread internet database system that lists to whom a particular domain name belongs, the contact information associated with the person or group that has registered that specific domain name, and other background information such as when the domain name was registered and when it will expire. It’s a helpful tool if you want to know who owns a domain name or website. Any changes you make to your WHOIS information, including contact information changes, will need to be reflected in DNS.
After making a change at either of these levels, DNS propagation technically requires up to 72 hours. However, in reality, this process usually takes about 3 hours.
So, what does that mean for you? Let’s say you’ve changed your domain name, and recorded the changes in DNS. If someone across the globe performs a DNS query (searches for your website) and their search is directed to a DNS server that has not yet been updated, they will be directed to the old address.
Why Does It Take So Long?
Even though DNS propagation is usually completed within a few short hours, there are a couple of reasons why it could theoretically take up to three days to fully update. Let’s explore a few of these.
Domain Name Registry
Certain types of changes may take longer to register throughout all DNS servers. For example, if you change the authoritative nameserver – the nameserver that holds the official, authoritative information on your domain name and web address – this change will need to be registered with the Top Level Domain nameserver.
The Top Level Domain nameserver is a root nameserver. This is a type of DNS nameserver that returns the IP addresses of the top-level domain – the ‘.com’ or ‘.org’ part of a web address. Any changes made in this zone can take a lot longer to register – even up to 48 hours.
Time To Live (TTL)
Every time you make a web search for a domain name, its DNS information will be stored in the records of every cache for a specific period of time. A cache is a temporary storage space for data that allows devices, apps, and web browsers to run quicker and more smoothly.
When you enter a domain name into a web browser, the browser initiates a DNS search process that takes place on multiple levels. First it contacts a DNS server, which may refer it to other DNS servers in search of the IP address that corresponds with the domain name entered. It has to locate the authoritative nameserver – the nameserver that holds the indisputably correct information about the IP address – and then send those results back to the browser.
At every stage of this process, different systems can retain information in their cache. Your computer’s operating system has a local cache that stores DNS information. So does your internet service provider – we’ll discuss that shortly. The primary function of a cache is to improve the performance of DNS queries, largely by making them faster.
The period of time that data is stored in a cache is called a Time to Live (TTL) value. Because of this, even when a record is changed, DNS will continue working with its previous information – the information stored in the cache – until the time is up and the cache clears and updates.
There are different types of records with different TTL values. In general, records that are expected to change very rarely have longer TTL values to prevent unnecessary searches.
If the TTL value for a cache containing information about your domain name is long (say, more than two hours, which is the average), then the propagation of your changes throughout the DNS system will take longer.
Internet Service Providers (ISPs)
Internet service providers all around the world also store information about domain names in caches. This allows them to perform a DNS search once, and then use the same DNS lookup results for any other users searching for the same website. It helps make internet traffic faster and is generally a good thing from a user-experience perspective.
However, these cached records are often held even longer than the TTL settings in DNS caches. This can significantly slow down the propagation process because as long as even one cache in the enormous global network of DNS servers holds onto the old DNS information, your changes won’t be fully propagated.
How to Speed up DNS Propagation
While most of these processes are out of your hands, there are a few methods you can try to speed up the propagation of your changes in DNS.
Clearing Your Local Cache
The first method is to try clearing your local DNS cache (the DNS cache on your computer’s operating system). The specific steps to do this will depend on which operating system your computer uses. The specific steps for each different operating system can be easily found online.
Pro tip: make sure you have an updated backup of all of your files before clearing your cache, in case something gets lost.
Lowering Your DNS Record’s TTL
You can also lower your DNS record’s TTL. This should be done a few days before making any changes to your domain name or web address. That way your old records will expire more quickly, and your changes will be reflected sooner in the system. Much like the previous method, the specifics of how to lower your DNS record’s TTL will depend on your web host.
Once again, this must be done before making changes to your domain name. Doing it retroactively won’t help you at all.
Can You Verify That Propagation Is Complete?
In short, it’s difficult to know with 100% accuracy. Verifying that all servers have updated to include your new information would require you to check every DNS server in the world – a slightly impractical goal.
However, there are a few software programs that can check propagation with decently accurate results. dnsresults.com is a free online option. There are different types of DNS records (they have names like A, CNAME, etc. – you can see them in the tools above), and you should check all of them individually to verify that your changes have been propagated.