What is DNS?
The Domain Name System (DNS) is used to convert IP addresses into readable domains such as bbc.co.uk. Without DNS everyone would have to remember random strings of number to access different websites, or at least Google’s IP address.
Why is it important?
Address (A) records and Mail Exchange (MX) records need to be kept up to date to ensure that access to your domain is maintained. Incorrect MX records will result in sporadic or failed delivery of emails to your business’s mail server, while incorrect A records will prevent access to your website.
How does it work?
When you interact with a domain such as bbc.co.uk, the browsing device runs through a series of requests to convert the URL into a machine-readable IP address every time you send emails, view websites or stream content.
The first stage in resolving a domain is to look at the local DNS cache. If your device can’t find the IP address it will start a DNS query with your Internet Service Provider’s recursive DNS servers. These servers have their own caches and are often able to return the required information to the user.
If the information isn’t held on the recursive DNS servers they send a query to the root nameservers. Root nameservers act like a switchboard as they don’t store the information requested but can point the query in the right direction.
The DNS query will then be transferred to TLD namservers then on to authoritative DNS servers, before finally reaching the authoritative nameservers that hold domain specific information that is stored in DNS records. Information such as address records is then passed back to the device via recursive DNS servers to store in its cache.
While it seems long winded, the whole process only takes milliseconds to complete. However the risk that the MX or A records are stored incorrectly is a real threat to businesses as potential customers will go elsewhere if they can’t access your information.