DOMAIN ADMIN TOOLS

Tips and tutorials for webmasters and domain administrators

What Is a Hostname?

A hostname is a label assigned to a device (a host) on a network. It distinguishes one device from another on a specific network or over the internet. The hostname for a computer on a home network may be something like new laptopGuest-Desktop, or FamilyPC.

Hostnames are also used by DNS servers so you can access a website by a common, easy-to-remember name. This way, you don’t have to remember a string of numbers (an IP address) to open a website.

A computer’s hostname may instead be referred to as a computer name, sitename, or nodename. You may also see hostname spelled as host name.

Examples of a Hostname

Each of the following is an example of a Fully Qualified Domain Name with its hostname written off to the side:

  • www.google.com: www
  • images.google.com: images
  • products.office.com: products
  • www.microsoft.com: www

The hostname (like products) is the text that precedes the domain name (for example, office), which is the text that comes before the top-level domain (.com).

How to Find a Hostname in Windows

Executing hostname from the Command Prompt is the easiest way to show the hostname of a computer.

hostname command prompt command in Windows 10

Never used Command Prompt before? See our How to Open Command Prompt tutorial for instructions. This method works in a terminal window in other operating systems, too, like macOS and Linux.

Using the ipconfig command to execute ipconfig /all is another method. Those results are more detailed and include information in addition to the hostname that you might not be interested in.

The net view command, one of the several net commands, is another way to see your hostname and the hostnames of other devices and computers on your network.

How to Change a Hostname in Windows

Another easy way to see the hostname of the computer you’re using is through System Properties, which also lets you change the hostname.

System Properties can be accessed from the Advanced system settings link inside the System applet in Control Panel. Or, press Win+R and then type control sysdm.cpl to go to the correct screen.

System Properties dialog box

More About Hostnames

Hostnames can’t contain a space because these names can only be alphabetical or alphanumerical. A hyphen is the only allowed symbol.

The www portion of a URL indicates a subdomain of a website, similar to products being a subdomain of office.com.

To access google.com’s images section, you must specify the images hostname in the URL. Likewise, the www hostname is always required unless you’re after a specific subdomain. 

For example, entering www.lifewire.com is technically always required instead of only lifewire.com. This is why some websites are unreachable unless you enter the www portion before the domain name.

However, most websites you visit open without specifying the www hostname—either because the web browser does it for you or because the website knows what you’re after.

What is a DNS Cache and How Does It Work

A DNS cache (sometimes called a DNS resolver cache) is a temporary database, maintained by a computer’s operating system, that contains records of all the recent visits and attempted visits to websites and other internet domains.

In other words, a DNS cache is just a memory of recent DNS lookups that your computer can quickly refer to when it’s trying to figure out how to load a website.

The information in this article applies to home users who haven’t changed their DNS settings.

The Purpose of a DNS Cache

The internet relies on the Domain Name System to maintain an index of all public websites and their corresponding IP addresses. You can think of it as a phone book.

With a phone book, we don’t have to memorize everyone’s phone number, which is the only way phones can communicate: with a number. In the same way, DNS is used so we can avoid having to memorize every website’s IP address, which is the only way network equipment can communicate with websites.

This is what happens behind the curtain when you ask your web browser to load a website.

You type in a URL like lifewire.com and your web browser asks your router for the IP address. The router has a DNS server address stored, so it asks the DNS server for the IP address of that hostname. The DNS server finds the IP address that belongs to lifewire.com and then is able to understand what website you’re asking for, after which your browser can then load the appropriate page.

This happens for every website you want to visit. Every time you visit a website by its hostname, the web browser initiates a request out to the internet, but this request cannot be completed until the site’s name is “converted” into an IP address.

The problem is that even though there are tons of public DNS servers your network can use to try to speed up the conversion/resolution process, it’s still quicker to have a local copy of the “phone book,” which is where DNS caches come into play.

The DNS cache attempts to speed up the process even more by handling the name resolution of recently visited addresses before the request is sent out to the internet

There are actually DNS caches at every hierarchy of the “lookup” process that ultimately gets your computer to load the website. The computer reaches your router, which contacts your ISP, which might hit another ISP before ending up at what’s called the “root DNS servers.” Each of those points in the process has a DNS cache for the same reason, which is to speed up the name resolution process.

How a DNS Cache Works

Before a browser issues its requests to the outside network, the computer intercepts each one and looks up the domain name in the DNS cache database. The database contains a list of all recently accessed domain names and the addresses that DNS calculated for them the first time a request was made.

The contents of a local DNS cache can be viewed on Windows using the command ipconfig /displaydns, with results similar to this:

docs.google.com
-------------------------------------
Record Name . . . . . : docs.google.com
Record Type . . . . . : 1
Time To Live . . . . : 21
Data Length . . . . . : 4
Section . . . . . . . : Answer
A (Host) Record . . . : 172.217.6.174

In DNS, the “A” record is the portion of the DNS entry that contains the IP address for the given host name. The DNS cache stores this address, the requested website name, and several other parameters from the host DNS entry.

What Is DNS Cache Poisoning?

A DNS cache becomes poisoned or polluted when unauthorized domain names or IP addresses are inserted into it.

Occasionally a cache may become corrupted because of technical glitches or administrative accidents, but DNS cache poisoning is typically associated with computer viruses or other network attacks that insert invalid DNS entries into the cache.

Poisoning causes client requests to be redirected to the wrong destinations, usually malicious websites or pages full of advertisements.

For example, if the docs.google.com record from above had a different “A” record, then when you entered docs.google.com in your web browser, you’d be taken somewhere else.

This poses a massive problem for popular websites. If an attacker redirects your request for Gmail.com, for example, to a website that looks like Gmail but isn’t, you might end up suffering from a phishing attack like whaling.

DNS Flushing: What It Does and How to Do It

When troubleshooting cache poisoning or other internet connectivity problems, a computer administrator may wish to flush (i.e. clear, reset, or erase) a DNS cache.

Since clearing the DNS cache removes all the entries, it deletes any invalid records too and forces your computer to repopulate those addresses the next time you try accessing those websites. These new addresses are taken from the DNS server your network is set up to use.

So, to use the example above, if the Gmail.com record was poisoned and redirecting you to a strange website, flushing the DNS is a good first step to getting the regular ​Gmail.com back again.

In Microsoft Windows, you can flush the local DNS cache using the ipconfig /flushdns command in a Command Prompt. You know it works when you see the Windows IP configuration successfully flushed the DNS Resolver Cacheor Successfully flushed the DNS Resolver Cachemessage.How to Flush and Clear Windows DNS Cache

Through a command terminal, macOS users should use dscacheutil -flushcache but know that there is not a “successful” message after it runs, so you’re not told if it worked. In some cases, Mac users will also have to kill the DNS responder (sudo killall -HUP mDNSResponder.) Linux users should enter the /etc/rc.d/init.d/nscd restart command. The exact command will vary based on your Linux distribution, though.

A router can have a DNS cache as well, which is why rebooting a router is often a troubleshooting step. For the same reason you might flush the DNS cache on your computer, you can reboot your router to clear the DNS entries stored in its temporary memory.

Best Free Public DNS Servers

The best free public DNS servers include GoogleQuad9OpenDNSCloudflareCleanBrowsingAlternate DNS, and AdGuard DNS.

Here’s a quick reference if you know what you’re doing, but we get into these services a lot more later in this article:

Best Free & Public DNS Servers
ProviderPrimary DNSSecondary DNS
Google8.8.8.88.8.4.4
Quad99.9.9.9149.112.112.112
OpenDNS Home208.67.222.222208.67.220.220
Cloudflare1.1.1.11.0.0.1
CleanBrowsing185.228.168.9185.228.169.9
Alternate DNS76.76.19.1976.223.122.150
AdGuard DNS94.140.14.1494.140.15.15

A list of additional free DNS servers can be found in the table near the bottom of the page.

What Are DNS Servers?

DNS servers translate the friendly domain name you enter into a browser (like lifewire.com) into the public IP address that’s needed for your device to actually communicate with that site.

Your ISP automatically assigns DNS servers when your smartphone or router connects to the internet but you don’t have to use those. There are lots of reasons you might want to try alternative ones (we get into many of them in Why Use Different DNS Servers? a bit further down the page) but privacy and speed are two big wins you could see from switching.

Primary DNS servers are sometimes called preferred DNS servers and secondary DNS servers sometimes alternate DNS servers. Primary and secondary DNS servers can be “mixed and matched” from different providers to protect you if the primary provider has problems.

Best Free & Public DNS Servers (Valid March 2021)

Below are more details on the best free DNS servers you can use instead of the ones assigned.

If you’re not sure, use the IPv4 DNS servers listed for a provider. These are the IP addresses that include periods. IPv6 IP addresses use colons.

GOOGLE: 8.8.8.8 & 8.8.4.4 

Google Public DNS website

Google Public DNS promises three core benefits: a faster browsing experience, improved security, and accurate results without redirects.

  • Primary DNS: 8.8.8.8
  • Secondary DNS: 8.8.4.4

Google also offers IPv6 versions:

  • Primary DNS: 2001:4860:4860::8888
  • Secondary DNS: 2001:4860:4860::8844

Google can achieve fast speeds with its public DNS servers because they’re hosted in data centers all around the world, meaning that when you attempt to access a web page using the IP addresses above, you’re directed to a server that’s nearest to you.

QUAD9: 9.9.9.9 & 149.112.112.112

Quad9 website

Quad9 has free public DNS servers that protect your computer and other devices from cyber threats by immediately and automatically blocking access to unsafe websites, without storing your personal data.

  • Primary DNS: 9.9.9.9
  • Secondary DNS: 149.112.112.112

There are also Quad 9 IPv6 DNS servers:

  • Primary DNS: 2620:fe::fe
  • Secondary DNS: 2620:fe::9

Quad9 does not filter content—only domains that are phishing or contain malware will be blocked. Quad9 also has an unsecured IPv4 public DNS at 9.9.9.10 (2620:fe::10 for IPv6).

OPENDNS: 208.67.222.222 & 208.67.220.220

OpenDNS public DNS server website

OpenDNS claims 100% reliability and up-time and is used by 90 million users around the world. The offer two sets of free public DNS servers, one of which is just for parental controls with dozens of filtering options.

  • Primary DNS: 208.67.222.222
  • Secondary DNS: 208.67.220.220

IPv6 addresses are also available:

  • Primary DNS: 2620:119:35::35
  • Secondary DNS: 2620:119:53::53

The servers above are for OpenDNS Home, which you can make a user account for to set up custom settings. The company also offers DNS servers that block adult content, called OpenDNS FamilyShield: 208.67.222.123 and 208.67.220.123 (shown here). A premium DNS offering is available, too, called OpenDNS VIP.

CLOUDFLARE: 1.1.1.1 & 1.0.0.1

Cloudflare 1.1.1.1 public DNS server website

Cloudflare built 1.1.1.1 to be the “fastest DNS service in the world” and will never log your IP address, never sell your data, and never use your data to target ads. 

  • Primary DNS: 1.1.1.1
  • Secondary DNS: 1.0.0.1

They also have IPv6 public DNS servers:

  • Primary DNS: 2606:4700:4700::1111
  • Secondary DNS: 2606:4700:4700::1001

There’s a 1.1.1.1 app for Android here and iOS here, for quick setup on mobile devices.

CLEANBROWSING: 185.228.168.9 & 185.228.169.9

CleanBrowsing public DNS server website

CleanBrowsing has three free public DNS server options: a security filter, adult filter, and family filter. These are the DNS servers for the security filter, the most basic of the three that updates hourly to block malware and phishing sites:

  • Primary DNS: 185.228.168.9
  • Secondary DNS: 185.228.169.9

IPv6 is also supported:

  • Primary DNS: 2a0d:2a00:1::2
  • Secondary DNS: 2a0d:2a00:2::2

The CleanBrowsing adult filter (185.228.168.10) prevents access to adult domains, and the family filter (185.228.168.168) blocks proxies, VPNs, and mixed adult content. More features can be had at a price: CleanBrowsing Plans.

ALTERNATE DNS: 76.76.19.19 & 76.223.122.150

Alternate DNS website

Alternate DNS is a free public DNS service that blocks ads before they reach your network.

  • Primary DNS: 76.76.19.19
  • Secondary DNS: 76.223.122.150

Alternate DNS has IPv6 DNS servers, too:

  • Primary DNS: 2001:4801:7825:103:be76:4eff:fe10:2e49
  • Secondary DNS: 2001:4800:780e:510:a8cf:392e:ff04:8982

You can sign up for free from their signup page. There’s also a Family Premium DNS option for $2.99 /month that blocks adult content.

ADGUARD DNS: 94.140.14.14 & 94.140.15.15

AdGuard DNS website

AdGuard DNS has two sets of DNS servers, both of which block ads in games, videos, apps, and web pages. The basic set of DNS servers are called the “Default” servers, and block not only ads but also malware and phishing websites:

  • Primary DNS: 94.140.14.14
  • Secondary DNS: 94.140.15.15

IPv6 is supported, too:

  • Primary DNS: 2a10:50c0::ad1:ff
  • Secondary DNS: 2a10:50c0::ad2:ff

There are also “Family protection” servers (94.140.14.15 and 2a10:50c0::bad1:ff) that block adult content plus everything included in the “Default” servers. Non-filtering servers are available if you’re not interested in blocking anything: 94.140.14.140 and 2a10:50c0::1:ff.

Why Use Different DNS Servers?

One reason you might want to change the DNS servers assigned by your ISP is if you suspect there’s a problem with the ones you’re using now. An easy way to test for a DNS server issue is by typing a website’s IP address into the browser. If you can reach the website with the IP address, but not the name, then the DNS server is likely having issues.

Another reason to change DNS servers is if you’re looking for better performing service. Many people complain that their ISP-maintained DNS servers are sluggish and contribute to a slower overall browsing experience.

Yet another common reason to use DNS servers from a third party is to prevent logging of your web activity and to circumvent the blocking of certain websites.

Know, however, that not all DNS servers avoid traffic logging. If that’s what you’re interested in, make sure you read through the FAQs on the DNS provider’s site to make sure it’s going to do (or not do) what you’re after.

If, on the other hand, you want to use the DNS servers that your specific ISP, like Verizon, AT&T, Comcast/XFINITY, etc., has determined is best, then don’t manually set DNS server addresses at all—just let them auto assign.

Finally, in case there was any confusion, free DNS servers do not give you free internet access. You still need an ISP to connect to for access—DNS servers just translate between IP addresses and domain names so that you can access websites with a human-readable name instead of a difficult-to-remember IP address.

Additional DNS Servers

Here are several more public DNS servers. Let us know if we’re missing any major providers.

OpenNIC has several DNS servers. Visit its website and select one that’s geographically nearby for the optimal performance.

More Free DNS Servers
ProviderPrimary DNSSecondary DNS
DNS.WATCH84.200.69.8084.200.70.40
Comodo Secure DNS8.26.56.268.20.247.20
CenturyLink (Level3)205.171.3.66205.171.202.166
SafeDNS195.46.39.39195.46.39.40
OpenNIC192.71.245.20894.247.43.254
Dyn216.146.35.35216.146.36.36
FreeDNS45.33.97.537.235.1.177
Yandex.DNS77.88.8.877.88.8.1
UncensoredDNS91.239.100.10089.233.43.71
Hurricane Electric74.82.42.42 
puntCAT109.69.8.51 
Neustar64.6.64.664.6.65.6
Fourth Estate45.77.165.19445.32.36.36

DNS servers are referred to as all sorts of names, like DNS server addresses, internet DNS servers, internet servers, DNS IP addresses, etc.