windows

Editing Windows Host File

📁 Editing Windows Host File

The Windows hosts file is a plain text file used to map hostnames to IP addresses. It is a critical, low-level component that can be used to override DNS settings locally.

Note: This procedure works ONLY IF the target network device(s) has a STATIC IP. Ensure you SET A DEVICE STATIC IP IF/AS NEEDED!

Common Reasons to Modify the Hosts File

Redirecting Domains: To point a domain to a different IP address for development or testing purposes.
Blocking Websites: To prevent access to specific websites by redirecting them to a non-existent or loopback IP (e.g., 0.0.0.0).
Testing Server Changes: To test changes on a staging server by pointing a domain to the staging server’s IP instead of the production server.
Improving Local Network Access & Performance:
- Used to create a static “direct link” to resolve local network hostnames when experiencing general network device access issues (e.g., DNS or network bugs).
- Resolves local network hostnames faster without querying a DNS server.
- Always triple check a system’s file and print sharing setup/settings before modifying the hosts file.
Bypassing DNS: To bypass the DNS settings for specific domains, useful for troubleshooting DNS issues (e.g., the static link bypass).

Procedure to Modify the Windows Hosts File

Step 1: Locate the Hosts File

The hosts file is located in the following directory: C:\Windows\System32\drivers\etc\hosts

Step 2: Open Notepad as Administrator

Search for Notepad: Press $\text{Windows} + \text{S}$, type Notepad.
Run as Administrator: Right-click on Notepad and select Run as administrator.

Step 3: Open the Hosts File in Notepad

In Notepad, click File $\rightarrow$ Open.
Navigate to C:\Windows\System32\drivers\etc.
In the lower right corner, change the file type from Text Documents (*.txt) to All Files (*.*).
Select the hosts file and click Open.

Step 4: Modify and Replace the Hosts File (Permissions Bypass)

Permissions Note: You typically cannot save the edited file directly back to the \etc folder unless using advanced tools. We use a workaround:

Add Entries: To add a new entry, type the IP address followed by a space or tab, then the hostname.
```
127.0.0.1 example.com
192.168.1.100 localtestserver
```
Save to Desktop: Click File $\rightarrow$ Save As and save the newly edited file to the system’s Desktop.
Show File Extensions: Through the Windows File Explorer, navigate to the Desktop. Under the “View” menu, mouse over “Show”, and then click “File Name Extensions”.
Rename File: The modified host file saved to the Desktop will show as hosts.txt. Rename it by removing the .txt extension, so the file simply reads hosts.
- Windows will warn you; accept the change.
Backup Original: Navigate back to the system’s host file directory: C:\Windows\System32\drivers\etc\
Rename the system’s current hosts file to hosts.old (accept the Windows warning/permission request).
Copy/Paste New File: Copy/paste or drag your modified hosts file from the Desktop to the system’s \etc directory.
- Windows will ask for Administrative Permission; accept it.
Clean Up: Go back to File Explorer and change the View settings back to NOT show file extensions.

Step 5: Flush DNS Cache (As Needed)

After modifying the hosts file, it is often necessary to flush the DNS cache for changes to take effect immediately.

Open Command Prompt as Administrator ($\text{Windows} + \text{S}$, type cmd, right-click $\rightarrow$ Run as administrator).
Run the command:
```
ipconfig /flushdns
```

📝 Example Modifications

Purpose	Example Entry
Redirecting to Localhost	`127.0.0.1 mytestsite.com`
Blocking a Website	`0.0.0.0 badwebsite.com`
Testing a New Server	`192.168.1.50 mysite.com`

Important Considerations

Backup: By renaming the original hosts file to hosts.old, you create an easy backup for reversion if needed.
Syntax: Ensure there are no typos. Use the format: [IP Address] [Hostname].
- Comments can be added using the # character at the start of the line.
Permissions: Modifying the hosts file requires administrative privileges.