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HOSTS file not being read

January 26, 2016 David Allan Web, 0

up vote76down voteaccepted

Based on my own experience and what I encountered while Googling, here are some things to try:

1. Did you check that it works correctly?

Changes to hosts should take effect immediately, but Windows caches name resolution data so for some time the old records may be used. Open a command line (Windows+R, cmd, Enter) and type:

ipconfig /flushdns

To drop the old data. To check if it works, use (assuming you have an ipv4 entry in your hosts for www.example.com, or an ipv6 entry in your hosts for ipv6.example.com):

ping www.example.com -n 1
ping -6 ipv6.example.com -n 1

And see if it uses the correct IP. If yes, your hosts file is fine and the problem is elsewhere.

Also, you can reset the NetBios cache with (open the console as an admin or it will fail):

nbtstat -R

You can check the current data in the DNS cache with:

ipconfig /displaydns | more

2. Basics

  • Is your hosts file named correctly? It should be hosts and not host, etc.
  • Is the extension correct? It should have no extension (hosts not hosts.txt) – be careful if you have configured windows to hide known extensions, check the properties to be sure: The correct hosts file’s type will show up as just “File”.
  • Did you follow the correct syntax? Did you accidentally prefix lines with a hash (#) which indicates comments?
  • Did you take care of all variants (www.example.com and example.com – safest to just add both)?

3. Whitespace

The format for each line is IP address, then a horizontal tab (escape code \t, ASCII HT, hex 0x09) or a single space (hex 0x20), then the host name, ie. www.example.com, then finally a carriage return followed by a line feed, (escape codes \r\n, ASCII CRLF, hex 0x0d 0x0a).

Sample entries, using Unicode control pictures to indicate control characters. (Don’t copy and paste these into your hosts file!)

192.0.2.1␉www.example.com␍␊
2001:db8:8:4::2␉ipv6.example.com␍␊

The individual bytes may be viewed in Notepad++ with the hex editor plugin. Notepad++ will also show special characters (View -> Show Symbol) so you can easily inspect the number and kind of whitespace characters.

If you copied and pasted hosts entries from somewhere, you may end up with multiple spaces. In theory hosts supports multiple spaces separating the two columns, but it’s another thing to try if nothing else works.

To be on the safe side, make sure all lines in your hosts file either use tabs or spaces, not both.

Lastly, terminate the file with a blank line.

4. Registry Key

There is a registry key specifying the location of the hosts file. Supposedly, Windows doesn’t actually support putting the hosts file in other locations, but you might want to check. The key is:

\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\DataBasePath

The entry should be:

%SystemRoot%\System32\drivers\etc

5. Permissions

Sometimes there are issues with permissions on the file, the file attributes, and similar things. To recreate the file with default permissions:

  1. Create a new text file on your desktop.
  2. Copy and paste the contents of your current hosts file into this file in Notepad.
  3. Save the new text file and rename it to hosts.
  4. Copy (do not move) the file to your %SystemRoot%\System32\drivers\etc directory, and overwrite the old file.

Last point is important: Copying works, moving doesn’t.

The local Users account must be able to read the hosts file. To make sure (in Windows 7):

  1. Navigate to %SystemRoot%\System32\drivers\etc in Windows Explorer.
  2. If you can’t see the hosts file, ensure you can see hidden and system files.
  3. Right-click on the hosts file and select Properties from the context menu.
  4. In the hosts Properties window, click on the Security tab.
  5. Examine the list of names in the Group or user names: box. If %COMPUTERNAME%\Users is present, click on it to view permissions.
  6. If Users is not present, or is present but does not have Read permission, click Edit....
  7. If Users is not present, click Add..., type Users, click Check Names, and click OK or press Enter.
  8. Select Users, and ensure Read & execute is checked in the Allow column. Click OK. If a Windows Security alert box pops up, choose Yes to continue.
  9. Click OK to close the hosts Properties window.
  10. Go up to section 1 of this answer and follow the directions to check if it’s working now.

6. Encoding

The hosts file should encoded in ANSI or UTF-8 without BOM. You can do this with File -> Save As.

7. Proxies

If you have a proxy configured, it may bypass the hosts file. The solution is to not use the proxy, or configure it to not do this.

To check, go to your Internet Explorer -> Internet Options -> Connections -> LAN settings. If everything is blank and “Automatically detect settings” is checked, you aren’t using a proxy.

8. DNS address

(This may also resolve proxy issues.)

Go to your network connections properties, then TCP/IP settings, and change the first DNS server to 127.0.0.1 (localhost). The second should probably be your actual DNS’s IP.

This is not necessary for the hosts file to work, but it may help in your case if something is configured strangely.

shareimprove this answer
THANK YOU SO MUCH SUPERBEST ! I’m almost crying, so many ours going crazy for a SPACE at the beggining of a blank entry between 2 lines. Thank you Thank you Thank you Thank you Thank you !!!!! – user228087 Jun 26 ’14 at 14:13
OMG!!! THANKS A TON!!! Been looking for a solution for 3 days now. I added example.com in my hosts file, but it didn’t work. When I added www.example.com, it worked instantly! This point may have been the last of the basics but it’s the top one in my view. Can’t thank you enough for posting this answer. Appreciate it!!! – Devner Aug 2 ’14 at 8:21
1
Another gotcha is that 64-bit versions of Windows redirect the System32 folder for 32-bit applications (such as Notepad++) so when you save the file shows up in the SystemWOW64 folder instead of System32. The best workaround is just use the Windows version of Notepad which is 64-bit. Second best is connecting to the administrative share (\\yourmachinename\c$\Windows\System32\drivers\etc) to open the file if you do use a 32-bit editor. – Tim Lewis Sep 19 ’14 at 14:36
4
Good post, but with a couple errors. 1) “Automatically detect settings” in IE can lead you to (even unnknowingly) use a proxy, if your network does actually provide proxy autoconfiguration. 2) Changing your DNS servers in the network settings hasn’t anything to do with how/when/if the hosts file is used, and changing it to 127.0.0.1 is effectively an error, unless you’re actually running a DNS server on your computer.– Massimo Sep 24 ’14 at 21:19
@Massimo, Re #1: You’re right. Re #2: I actually added due to some personal experience, where a computer with a bunch of strange configurations could be made to use the hosts file with that method. I didn’t investigate to see if the DNS address was definitely the problem – but I decided to leave that step in with a note. Feel free to edit the question if you like. – Superbest Sep 24 ’14 at 22:56

up vote9down vote

Make sure you have put the ipaddress first and then the “domain” like this:

127.0.0.1   bo.dev
127.0.0.1   www.bo.dev
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2
I prefer to use a single line: 127.0.0.1 bo.dev www.bo.dev ftp.bo.dev – Xhynk Mar 28 ’14 at 16:59

up vote5down vote

Please add checking file permissions. I found that even though I had Local Admin rights to the computer and thus to hosts. It was not until I added local users to the hosts file permissions with Read and Read & Execute and then a ipconfig /flushdns That the hosts became active.

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1
That was it! I’ve been baffled by this problem for years. I added (machine)\USERS with Read and Read & execute permissions and after ipconfig /flushdns it worked. Thank you so much. I am very pleased to finally have my hosts file back. – Clement Cherlin Jun 10 ’15 at 15:37

up vote4down vote

In my cases I tried Windows 7 created file: C:\Windows\System32\drivers\etc\hosts.ics.

hosts.ics:

# This file has been automatically generated for use by Microsoft Internet
# Connection Sharing. It contains the mappings of IP addresses to host names
# for the home network. Please do not make changes to the HOSTS.ICS file.
# Any changes may result in a loss of connectivity between machines on the
# local network.

As the result, Windows ignores settings in C:\Windows\System32\drivers\etc\hosts and uses it from hosts.ics.

shareimprove this answer
From support.microsoft.com/en-us/kb/309642/en-us, which is old so maybe no longer accurate: “The Hosts.ics file is used by ICS to store information about dynamically configured clients. Avoid making changes to this file to prevent the loss of connectivity or data. The Hosts file (with no file name extension) is the file to which you add information about statically configured clients.” So, I’d NOT expect Windows to ignore the Hosts file just because Hosts.ics is present. Something else might be causing Windows to ignore your Hosts files, like maybe a wrong (but hidden) extension. – Arjan Jun 21 ’15 at 13:07
1
I see this information. But I don`t know, why I was able to make hosts work only I edited hosts.ics. Before to edit hosts.ics, I tried all methods from this topic, but hosts does not work. – Unick Jun 22 ’15 at 10:06

up vote1down vote

Have spent hours, probably days on this.

IBM Trusteer Endpoint Rapport security can cause this problem.

I had added mysite.com to its list of trusted sites.

I think as part of its security it prevents malware or viruses diverting you to alternative sites.

Took mysite of the list of trusted sites and it no longer checks and “corrects” my hosts file diversion.

Hope that helps somebody resolve their problem.

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up vote0down vote

In windows, make sure HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\DataBasePath is pointed to the directory of the hosts file.

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up vote0down vote

One problem missed in the discussion above is unqualified names in the hosts file. Your network settings might kick in at that point and automatically add your own domain to the end of an unqualified domain. Consequently the name might not resolve, or worse yet, resolve to a completely different machine.

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up vote0down vote

On my case the issue was that I was copying a hosts file from an encrypted directory and overriding the etc/hosts with that. I had to look at properties and uncheck the “encrypt file” checkbox.

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protected by Community♦ Aug 26 ’15 at 17:02

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