There are several different DNS servers your computer could be using.
I’ll look at how to quickly find out which servers your computer is configured to use, and then I’ll discuss a couple of situations where you might want to use something different.
Become a Patron of Ask Leo! and go ad-free!
The DNS you use
In my opinion, the fastest and easiest way to determine what DNS server you’re using is to use the Windows Command Prompt.
In Windows 10, right-click on the Start menu and click on Command Prompt. In most other versions of Windows, click on Start, then All Programs, then Accessories, and finally on Command prompt.
Type “ipconfig /all” followed by Enter. You’ll get a lot of information.
There may be several networking adapters. Look for the one with a recognizable IPv4 address, most often starting with 192.168 — an IP address assigned by your router. In the example shown above, the IP address is 10.1.10.177.
In the midst of the information, you can see “DNS Servers” listed. Typically, there are multiple servers that provide backup access if one fails to respond.
|DNS Servers . . . . . . . . . . . :||2001:558:feed::1|
In my case, I have several DNS servers listed: two IPv6 addresses and an IPv4 address, all pointing to my router, plus three IP addresses for external DNS services.
Yours will almost certainly be different.
Where DNS settings come from
Unless you override them, DNS settings are assigned by your ISP. When your router connects to the internet and asks your ISP for an IP address, the ISP’s response includes the IP addresses of one or more DNS servers. When your computer then starts up and asks your router for an IP address on your local network, the router responds in one of three ways:
- It simply passes on the DNS information it was given by your ISP.
- It returns its own IP address, meaning that the router itself will act as your DNS server.
- It returns a combination of both, as you’ve seen in my example above.
When a router acts as your DNS server, it can result in a speed improvement. Each time a DNS request is made, the router remembers the answer. Then, when a request for the same information is made again — a common occurrence — it can simply return the response it already knows without needing to reach out to a DNS server on the internet.
If you find that your computer’s DNS is set to be your router’s IP address (most commonly a single DNS server is listed, and it’s the same as the “Default Gateway” listed in the ipconfig output), then to see what DNS server you’re really using for requests that the router can’t fulfill, you’ll need to check the router’s configuration. Exactly how you do that depends on your router, so check the documentation that came with it.
Why change DNS?
In most cases, it’s quite appropriate to use the DNS servers provided by your ISP, but you’re generally not required to.
There are two reasons to consider alternative DNS services: speed and security.
Some public DNS servers are designed to be fast. Perhaps more pragmatically, some ISP’s DNS servers aren’t designed to be fast; they’re just in place because the ISP is “supposed” to provide DNS services. Switching to a different service can speed up a DNS request’s response time. If you find it consistently takes a long time the very first time you visit a web site, or you see phrases like “resolving <domain name>” in your browser’s status bar for a long time, then trying a faster DNS service might be an alternative.
Google’s Public DNS is one such service.
DNS services such as OpenDNS and the new Quad9 (named after their base DNS server IP address: 220.127.116.11) add an additional service: security. Both block known malicious sites. If you have malware, or are in the process of falling for a phishing attempt, these services can protect you by blocking or redirecting a request that would land you on a site known to be malicious. OpenDNS also has additional adult-content and custom filtering available.
Alternative DNS servers aren’t for everyone, and they certainly aren’t required, but if you’re experiencing a DNS-related speed issue, or are looking for additional protection, they might be worth investigating.
I’ll review how to change your DNS settings in a follow-up article.