What is DNS? | Trusted reviews

The Domain Name System (DNS) maps a friendly URL, such as www.trustedreviews.com, to the numeric IP (Internet Protocol) address that identifies its server on the Internet.

You can think of it as the telephone directory of the Internet, allowing you to look up the address associated with a specific domain name when your browser requests it.

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Where are DNS records stored?

Each domain name has a DNS record that indicates which IP addresses the domain and its various subdomains should direct people to. This is submitted by the domain administrator to their registrar – the service with which they registered the domain name.

Most domain registrars also provide DNS hosting, operating name servers that contain and respond to queries for the IP address your domain name points to, although you can use a third-party name server. The one you choose will be the authoritative name server for that domain and store its DNS record.

How are DNS records searched?

When you type in a URL, a recursive DNS resolver will look it up. Your ISP usually handles DNS resolution for you, but you can configure your operating system to use a different resolver, such as Google 8.8.8.8 or Cloudflare 1.1.1.1.

Using a reputable third-party resolver can improve lookup speed and reliability, escape censorship your ISP may apply to their DNS lookups, and may be – but certainly not always – be less susceptible to DNS hijacking or hacking attacks. cache poisoning affecting regional DNS resolvers.

Once the DNS resolver receives your request for the IP address associated with the domain name you typed into the browser bar, it then forwards the request to one of 13 world root nameservers, each of which is in makes an international network of hundreds of servers. The root zone is the highest level in the Internet addressing hierarchy, above even top-level domains such as .com, .net, and .co.uk.

The root server tells it which top-level domain name server it should request (.com in the case of trusted notices). The resolver then sends a query to that TLD server, which tells it where the authoritative name server for that domain is located. The resolver finally queries this authoritative server: the domain’s DNS host, which will ultimately tell the resolver the IP address it needs. All of this takes less than a tenth of a second according to some old but oft-quoted data from Yahoo.

Going through this whole process is actually only rarely necessary, because once a resolver has looked up a domain name, it caches (temporarily stores) the routing information associating it with the IP address to which he points. How long this information is cached depends on the TTL (time to live) value in the domain’s DNS record.

Your operating system will also maintain its own DNS resolver cache to further speed up browsing.

IP addresses

I referred to IP addresses as numeric, but that’s a description of IPv4, which uses 32-bit addresses that take the form of four numbers divided by dots, 192.0.2.0 for example.

Although there are approximately 4.3 billion potential IPv4 addresses, we started running out of them more than a decade ago, and the last remaining block of addresses was released in 2019.

IPv4’s successor, IPv6, uses 128-bit alphanumeric hexadecimal addresses that are usually expressed as eight groups of numbers, such as 2001:0db8:0001:0000:0000:0ab9:C0A8:0102. It’s admittedly not nearly as easy to remember, though you can omit the leading zeros to make it 2001:db8:1::ab9:C0A8:102 – note that the digits 0000 disappear completely.

IPv6 adoption and implementation remains disappointing – I am currently connected to an ISP that has failed to implement it properly. However, the technology is mature and the format allows for 340 trillion trillion unique IP addresses, so it is highly unlikely that we will run out of them, ensuring the future stability of Internet addressing.

Every Internet connection has an IP address. Some ISPs, especially mobile broadband providers, alternate IP addresses between their user pools (dynamic IP address assignment), so you won’t always have the same IP address. Others, especially landlines, usually have static IP addresses – a unique IP address that always points to your connection – which can be used to reliably stream content to the outside world.

Similarly, your router assigns each device on your local network a unique IP address internally, usually in the 192.xxx range, but these are only for internal network addressing.

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The secure way to enjoy the web without compromising speed is now 34% off at £34.13 per year, which equals £2.84 per month, with coverage for up to 5 devices.

Compatible with Android™ and iOS®

  • Kaspersky
  • Was £52.50
  • £34.13/year (monthly equivalent of £2.84)

See the offer

Content Delivery Networks

These days, it’s rare for major websites that receive a lot of outside traffic to all be accessible through a single IP address. Instead, many sites use a Content Delivery Network (CDN) such as Akamai, Cloudflare, or Fastly.

These services hide the real IP address that your server lives on. Their nameservers route traffic through IP addresses owned by the CDN, which then routes traffic to the origin server (i.e. the server that actually hosts the site) as efficiently as possible.

Using a CDN not only protects against threats such as Distributed Denial of Service (DDoS) attacks by spreading traffic across multiple IP addresses without revealing the actual address of the origin server, but also means that Loading speeds can be improved by directing users to different parts of the world through a local data center operated by the CDN.

CDNs can also cache – keep short-term copies of – web page content in their data centers, allowing it to be served faster to a site’s many users without having to retrieve it each time. on the origin server.

Combined with technologies such as file compression and script minification (in which code in languages ​​such as HTML and JavaScript is reduced to a version that uses the fewest characters possible, saving bandwidth), a CDN can provide significant performance improvements.

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