Testing Your Web Site Before Changing DNS


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When migrating your site to a new server, you want to test your site before updating the DNS to point to the new server. To do this you can use your computer’s hosts file to force your computer to visit the new server when visiting your domain name.

What is a Hosts File?

Your computer’s hosts file is a local repository for resolving a domain name to an IP. This method predates modern DNS systems. Your computer will check the hosts file before making any DNS requests to resolve a domain. This allows you to adjust your hosts file to force your computer to visit a different IP address when visiting a domain name.

Example

Below is an example from a Windows hosts file that shows google.com and www.google.com pointing to a different IP address than what is reported by a DNS lookup.

# Copyright (c) 1993-2009 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
#      102.54.94.97     rhino.acme.com          # source server
#       38.25.63.10     x.acme.com              # x client host

# localhost name resolution is handled within DNS itself.
#	127.0.0.1       localhost
#	::1             localhost
192.168.1.204 google.com
192.168.1.204 www.google.com

How to Edit the Hosts File

Windows PC (Windows 95, 98, Me, NT, 2000, XP, 2003, Vista, 7, 8, 10)

  1. Open Notepad as Administrator.
    1. Click the start menu, in the run box type “notepad.exe”.
    2. You should see an icon for the Notepad application, right click on this icon and click Run as Administrator.
    3. You will likely receive a warning message asking if you are sure you would like to proceed. Click on Yes.
  2. In Notepad click File–>Open.
  3. You will then navigate to the following directory:
    • Windows NT, 2000, XP, 2003, Vista, 7, 8, 10:
      C:\windows\system32\drivers\etc\hosts
    • Windows 95, 98, Me:
      C:\windows\hosts
      Please note that the file type drop-down menu needs to be changed to “All Files” to see the hosts file.
  4. On the last line add your entry as shown below then save and close Notepad. This example assumes we want to point domainname.com to 0.0.0.0.
    • If you recieve an error when saving the file, you may need to temporarily disable any Anti-Virus running while you make this change. Normally you don’t want this file to be editable.
    • You will replace the 0.0.0.0 with the IP Address of your site in our system. The IP Address that you need to use can be found in your cPanel, WCP, or New Account Information email.
      0.0.0.0 domainname.com

Mac OS

  1. Open a finder window and navigate to your Applications folder.
  2. Open the Utilities folder.
  3. Locate the Terminal app and double-click it.
  4. When the terminal opens, enter this command:
    • Mac OS 10.6 and higher:
      sudo nano /etc/hosts
    • Mac OS 10.5 and below:
      sudo nano /private/etc/hosts
  5. Enter your Mac user’s password when prompted.
  6. On the last line add your entry as shown below. This example assumes we want to point domainname.com to 0.0.0.0.
    • Replace 0.0.0.0 with the IP Address provided in your new account information email.
      0.0.0.0 domainname.com
  7. Press CMD-x, then press y when prompted to save your changes.

Linux

  1. SSH into your console or open your terminal if you run a GUI on your Linux machine.
  2. Enter the following command:
    sudo nano /etc/hosts
  3. Enter your root password when prompted.
  4. On the last line add your entry as shown below. This example assumes we want to point domainname.com to 0.0.0.0.
    • Replace 0.0.0.0 with the IP address provided in your new account information email.
      0.0.0.0 domainname.com
  5. Press ctrl-x, and then press y when prompted to save your changes.

Note: If you plan to test with the www version of your domain name, you must add an entry for the www version of your domain to the hosts file. You may also need to flush your computer’s DNS resolver cache after making these changes as well.

Additional Resources


5 Steps to Make Migrations Painless
Installing WordPress on Your Website