This article applies to:
- Acronis Software
What is DNS
DNS (Domain Name System) - is a system that provides resolution of hostnames to IP addresses. Every time you try to connect to a host (e.g. google.com) your machine first performs a request to DNS. After getting the IP address from DNS the machine establishes connection to the respective IP address.
Operating systems have also local instruments to add name resolution rules (hosts file). These rules by default have bigger priority than other rules.
How machine resolves a host:
- Checks the hosts file.
- Checks DNS cache.
- If there is no DNS cache or it is expired the machine queries DNS server about specific host.
- Hostname is not resolved.
- Hostname is resolved incorrectly.
Troubleshooting in Windows
To verify the problem perform manual lookup of the hostname. Open CMD (Start -> Run -> type "cmd" -> Hit Enter). Issue command:
e.g. nslookup google.com
This should output the IP addresses of the host (e.g. google.com), if the command works.
If the command returns an error, please check the DNS configuration on the machine:
- Issue command: ipconfig /all.
- Look into the output and search for "DNS Servers". If no servers are specified, you have to specify them in adapter settings, or if your servers are sent to you from your DHCP server, you should check if that server is configured correctly. If you are sure that all settings are correct on your side, please contact your Internet Service Provider.
If the hostname is not resolved to the correct IP you should:
- Check the contents of the file "C:\Windows\System32\drivers\etc\hosts" and see if that host is present there with a wrong ip.
- If it is not present there please try to clean DNS cache: ipconfig /flushdns
- If the problem persists try to use some other DNS server such as Google Public DNS 22.214.171.124 or contact your Internet Service Provider.