Fixing the "Unknown DNS Server" problem (TP-LINK / Archer C9)
Note: If you cannot fix the problem after you follow these instructions, maybe we can help. Get help from RouterCheck Support.
Understanding the "Unknown DNS Server" problem
DNS is the process that turns website names into the internet addresses that lets your computer connect to websites. This process happens by means of a DNS Server which acts like an automatic 411 system behind the scenes. Things happen so quickly and seamlessly, you might not even know that they're working, but the health of the DNS system is critical to your web browsing experience.
There are many DNS Servers running on the internet. Popular ones include Google DNS and OpenDNS, both of which are efficient and reliable. The one that you use is often configured in your router. If you don't set a DNS Server to use in your router, the one you use is often provided for you automatically by your ISP.
When hackers compromise routers, they often modify the router's DNS settings so that they can control your DNS system. This is bad because they often configure your router to use a rogue DNS Server that they control. This allows them to misdirect your browsing whenever they like.
RouterCheck analyzes the router's DNS settings to help ensure that they aren't tampered with.
Sometimes it finds that a DNS Server has been configured that is unknown to RouterCheck. This is normal behavior and happens quite often. There are thousands of DNS Servers running on the internet, and it's impossible to have information about all of them. So this makes it difficult for RouterCheck to positively verify that the DNS system is healthy. It doesn't mean that anything is necessarily wrong, you should just be aware and proceed with caution.
What is the risk of not fixing this problem?
If your DNS requests are being serviced by a rogue DNS Server that's being controlled by a hacker, your entire network is at risk. They can do things such as redirect any requests you make to a sensitive site (such as your online bank) to a site that they control. These rogue sites look identical to the ones you're used to, but their sole purpose is to trick you into giving up your private information so that they can benefit. Misdirected DNS has also been used to direct victims to pages containing malware that infects their computer with viruses, further compromising the network.
The RouterCheck development team is currently building a system to help detect rogue DNS Servers, something that up until now was not possible. Look for this new functionality in future versions of RouterCheck.
Often, it's a good idea to look through the router's documentation to learn how to fix problems. Go to the vendor's support site where you can download documentation.
How to fix the "Unknown DNS Server" problem
Step 1: Log into your router
You use a web browser to interact with your router and fix its configuration problems. However, before you can interact with your browser, you must log into it. RouterCheck can give you detailed instructions for logging in to your router.
Step 2: If you log in successfully, your router's home page opens.
Step 3: Navigate to the DNS Settings page.
You want to find the page that allows you to configure the DNS Server settings. The page name may be similar to:
- Internet Options
- WAN Options
- DNS Settings
Navigate to this page by clicking the appropriate menu items and buttons.
Step 4: If you are successful, your router's DNS Settings page opens.
Step 5: Select a new DNS Server
A possible solution to DNS-related problems is to explicitely set the DNS Server you'd like to use in your router's configuration. The first step to doing that is to choose which DNS Server you'd like to use
There are many publically-available DNS Servers that you may use for free. Popular choices invlude Google DNS and OpenDNS. Alternatively, speak with your ISP to learn how to configre your router to use their DNS Servers.
Step 6: Configure your DNS Server settings
On the page with the DNS Server settings, you should find several boxes where you can choose the DNS Servers that you'd like to use. It's advisable to use at least two servers, so that if there's a problem contacting the first, the second one may be used. Often, these are referred to as Primary and Secondary servers.
Fill in the information that you have about the DNS Server that you've chosen. This will need to be done in the form of IP addresses, since a DNS Server would be necessary to resolve a regular website name.
Step 7: Re-run RouterCheck.
Now that you've fixed your problem, run RouterCheck again to verify that you have really fixed the problem.
Fix a problem on your router
- Bad Administrator Password
- Remote Administration is on
- Ports are open
- Router is Pingable from the Internet
- Local DNS Server
- Unknown DNS Server
- DNS Server Resolves Non-existent Domains
- Rogue DNS Servers
- Actual DNS Servers
- No Wifi security is being used
- WEP Wifi security is being used
- WPA Wifi security is being used
- WPS is turned on
- Wifi security could not be determined
- Tested Vulnerability Failure
- Lookup Vulnerability Failure
Learn how to use your router
- How to log in to your router
- How to reset a router to factory defaults
- How to load new firmware onto your router
- Get the default administrator password for your router.
- How to find the IP Address of your router
- Find firmware to install on your router
- Find user guides for your router
- If you are still having difficulties, maybe we can help.