2 posts tagged with "dns"

If your browser reports DNS_PROBE_FINISHED_NXDOMAIN, it means that it cannot determine the IP address of the requested site. This can happen for a variety of reasons:

• The domain name is not present in DNS servers or its registration has expired.
• The server responsible for the domain zone is unavailable.
• DNS is configured incorrectly on the device.
• Interference from a VPN, antivirus, or firewall.
• Issues with the internet service provider.

The accompanying error message may look slightly different in different browsers:

• Google Chrome: «This site can’t be reached».
• Mozilla Firefox: «Hmm. We’re having trouble finding that site».
• Microsoft Edge: «Hmm… can’t reach this page».
• Safari: «Safari Can’t Find the Server».

How to identify the cause of the error?​

1. Check the domain status​

First, make sure the entered address is correct. If everything is correct, check the domain registration using ICANN Lookup. Enter the URL and see if the domain is active.

2. Check availability via proxy​

Try accessing the site using a proxy, VPN, or another network (for example, your mobile provider). If the site opens in this scenario, then the issue is most likely related to the settings on your device or network.

How to fix DNS_PROBE_FINISHED_NXDOMAIN​

Clearing the DNS cache​

Sometimes the browser or system saves outdated DNS records. Clearing the cache helps refresh them.

• Windows:

1. Open Command Prompt as administrator: Start → type cmd in the search bar and press Enter.
2. Run the command:

ipconfig /flushdns

3.  Restart your browser.

• macOS:

1. Open Terminal: on the keyboard, press cmd + space, type Terminal, and press Enter.
2. Enter:

sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

3. Press Enter.

• Google Chrome:

1. In the browser’s address bar, enter:

chrome://net-internals/#dns

2. Click Clear host cache.

Updating the IP address​

If clearing the cache did not help, try obtaining a new IP address.

• Windows:

ipconfig /release
ipconfig /renew
netsh int ip set dns
netsh winsock reset

 Restart your system.

• macOS:

1. Go to System Preferences → Network.
2. Open the connection → Advanced → TCP/IP.
3. Click Renew DHCP Lease.

Using alternative DNS servers​

The issue might be related to your provider’s DNS servers. Try using Google DNS (8.8.8.8, 8.8.4.4) or Cloudflare DNS (1.1.1.1, 1.0.0.1).

• Windows:

1. Open Control Panel → Network and Internet → Network and Sharing Center.
2. Select the active connection → Properties.
3. In the Internet Protocol Version 4 (TCP/IPv4) section, specify:

• Primary DNS: 8.8.8.8

• Secondary DNS: 8.8.4.4

• macOS:

1. Open System Preferences.
2. Go to Network.
3. Select the active connection (for example, Wi-Fi or Ethernet) in the left column.
4. Click the Advanced button.
5. Go to the DNS tab.
6. In the DNS Servers section, click the + button and add the following DNS servers:

• 8.8.8.8 (Google DNS)
• 8.8.4.4 (Google DNS)

 or

• 1.1.1.1 (Cloudflare DNS)
• 1.0.0.1 (Cloudflare DNS)

7. Click OK, then Apply.

Restarting the DNS Client Service (Windows)​

1. Open Command Prompt as administrator.
2. Type:

net stop dnscache
net start dnscache

 Checking the hosts file​

The hosts file may contain incorrect entries that block access to the site.

• Windows:

1. Open Notepad as administrator.
2. Open the file  (File  →  Open):

C:\Windows\System32\drivers\etc\hosts 

3. Удалите строки, содержащие проблемный домен.

• macOS:

1. Open the hosts file in a text editor:

sudo nano /etc/hosts

2. Delete the lines that contain the problematic domain.
3. Save the file using the keyboard shortcut Ctrl + O, and then exit the editor using Ctrl + X. 

Resetting chrome flags​

Hidden browser settings might have changed.

1. Enter in the address bar:

chrome://flags/

2. Click Reset all to default.

Disabling antivirus and VPN​

Some antivirus programs or VPN services may block DNS queries. Temporarily disable them and check if the site is now accessible.

Checking CDN settings​

If the site uses Cloudflare or another CDN, try temporarily disabling proxying for that domain in your CDN control panel.

Restarting the router​

Sometimes the issue is related to the router. Try the following:

1. Turn it off for 5 minutes.
2. Turn it on and check the connection.

Conclusion​

The DNS_PROBE_FINISHED_NXDOMAIN error is related to DNS issues. You can resolve it by clearing the cache, changing DNS servers, checking the domain, or adjusting system settings. If nothing helps, contact your internet service provider.

Introduction​

If you have ever configured a mail server or encountered reverse DNS checks for other reasons, you have likely heard about PTR records. But what exactly are they? Why can you often not set up a PTR record yourself? Let’s figure it out!

What is a PTR record?​

A PTR (Pointer) record is a type of DNS record used for reverse mapping of IP addresses to domain names. Unlike standard A records (which map a domain to an IP), PTR records let you determine which domain a particular IP address belongs to.

How does a PTR record work?​

When a server receives an incoming connection, it can request a reverse DNS (rDNS) lookup for the sender’s IP address. If a PTR record is configured, it will return the corresponding domain name. This is important for:

• Setting up mail servers (SMTP servers often require PTR records for proper email delivery and to avoid spam issues);
• Identifying IP addresses in logs and enhancing security;
• Ensuring correct operation of certain services that depend on rDNS.

Why can’t I set up a PTR record on my own?​

Many users with access to manage DNS records expect they can create a PTR record just like an A or CNAME record. However, here’s the main issue: PTR records are not configured in your DNS hosting; they are set up by the IP address provider (ISP, data center, or hosting provider).

Key reasons:​

1. Control of IP addresses – PTR records belong to the owner of the IP pool. If you have a dedicated server or VPS, your hosting provider owns the IP address and must configure the record.
2. Lack of rDNS management – Even if you have DNS management access, the reverse DNS zone (in-addr.arpa) is controlled by the owner of the IP address block.
3. Provider requirements – Some hosting providers only allow you to configure PTR through support tickets, not via a control panel.
4. Dynamic IP addresses – If your IP address is dynamic (for example, with a home internet connection), your ISP will not let you set a personalized PTR record.

How to configure a PTR record?​

1. Contact your provider​

To create or change a PTR record, you need to contact the hosting provider or ISP that allocated your IP address. This is usually done by opening a support ticket.

2. Specify the required domain​

Typically, the provider will require the PTR record to point to a real domain, which is already set up and resolvable via an A record.

3. Verify the configuration​

After changing the PTR record, it’s worth checking its functionality using the following commands:

Windows:

nslookup 123.123.123.123

Linux and MacOS:

dig -x 123.123.123.123

Conclusion​

A PTR record is an important part of DNS, especially for mail servers. However, you cannot set up this record without the involvement of the IP address owner. If you need to create a PTR record, contact your hosting provider to discuss the possibility of configuring it. Doing so will help you avoid email delivery problems and increase trust in your server.