The DNS system is an inseparable part of how the internet works. It’s what lets a page’s content load once you type its address into your browser’s address bar. DNS propagation is one of those moments when a website temporarily stops working for you. Find out exactly what propagation is and how long it can take.
What is a DNS server?
DNS stands for Domain Name System. It is a protocol whose main function is to translate a domain name into numerical data that computers can understand. The main job of a DNS server is to look up the IP address of a given site once you, as an internet user, type the site’s name into the address bar. DNS servers are linked together into one huge network, starting with your internet provider, through hosting providers, all the way to root servers. They hold a hierarchical database containing top-level domains, so-called TLDs, and second-level domains. TLDs are split into two subcategories: country-code and generic. Country-code TLDs refer, as the name suggests, to a country — for example Poland = .pl, Germany = .de, Spain = .es, and so on. Generic TLDs include:
- commercial = .com
- business = .biz
- government = .gov
- education = .edu.
DNS servers are also used to handle second-level, or regional, domain addresses, such as
.slaskie.pl or katowice.pl.
Browsers and the DNS system
DNS servers work closely with your browser. The whole process begins the moment an internet user starts typing a website address into the browser, so that within moments the entire content of the page appears before their eyes. As unlikely as it may seem, while we wait for a page to load, the network devices and the device we’re using are firing off dozens of DNS queries. The whole process looks like this:
- the web browser asks the operating system for the IP address
- the operating system checks its cache to see whether the address already exists and whether you’ve visited that site before (if it’s a new address, a query is sent to the DNS server configured in the system)
- in most cases, the first DNS server is the router at home or in the office. The router repeats the process and checks its own memory to see whether it already knows the domain’s address
- the next step, if it’s a new address, is that the query is sent to your internet provider’s DNS servers, where the same process is repeated
- the DNS servers pass the query on to further servers
- if there’s a positive response — meaning the domain in question is handled by a specific DNS server — the return trip begins
- the DNS server responsible for the domain replies with the correct IP address, which travels back to the web browser
- for a new site, the DNS server remembers the IP address and stores it in its cache (this depends on settings and can be changed).
What is DNS propagation
DNS propagation is the process of spreading information across the internet about a domain’s new IP address, or about it now being handled by different DNS servers. This is necessary so that every server returns the correct answer and redirects the user to the right website. Today’s network is vast, so, as you can imagine, this is a fairly lengthy process. Propagation also refers to the process of registering a new domain or restoring a site — for example, after a suspension. In practice, this can create certain complications. Because DNS servers may resolve a different server IP than before at any given moment, some users may reach the new server while others still land on the old one.
What affects propagation?
The most important factor in propagation is time. You can try to speed up the whole process thanks to certain actions you can take yourself. DNS propagation time is affected mainly by:
- refreshing DNS records in the domain registry
- the TTL (Time To Live) parameter — the length of time information about a given domain is cached
- refreshing Google’s DNS cache
- your computer’s cache — in this case you can refresh the cache yourself using the appropriate commands.
DNS propagation can take up to 70 hours. How long the whole process takes depends on many factors. We can’t speed it up at every stage, so it’s best to be patient and let the process run its course on its own.