How to Reset the Hosts File to Default (Windows, Mac, Linux)

To reset the hosts file to default, replace its contents with the clean default for your OS, save it with admin rights, then flush DNS. This undoes any custom redirects, including adware/malware injections or broken entries, and restores normal domain resolution. Always make a quick backup first; the steps below cover Windows, macOS and Linux.

Back up the current file first (30 seconds)

# macOS / Linux
sudo cp /etc/hosts /etc/hosts.bak

# Windows PowerShell (as administrator)
Copy-Item C:\Windows\System32\drivers\etc\hosts C:\Windows\System32\drivers\etc\hosts.bak

If anything you needed was in there, you can restore it from hosts.bak.

Reset the hosts file on Windows 10 and 11

# 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

ipconfig /flushdns

On Windows, localhost resolution is built in, so the loopback lines stay commented in the default. For editing methods and permission fixes, see edit the hosts file on Windows and edit the hosts file as administrator.

Reset the hosts file on macOS

Open Terminal and write the macOS default:

sudo tee /etc/hosts >/dev/null <<'EOF'
##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting. Do not change this entry.
##
127.0.0.1	localhost
255.255.255.255	broadcasthost
::1 localhost
EOF

Then flush the DNS cache:

sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder

More context: edit the hosts file on Mac and flush DNS on Mac.

Reset the hosts file on Linux

sudo tee /etc/hosts >/dev/null <<'EOF'
127.0.0.1	localhost
127.0.1.1	$(hostname)
::1 localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
EOF
sudo resolvectl flush-caches

The 127.0.1.1 <hostname> line is Debian/Ubuntu convention; keep your machine's hostname there. If a reset fails with "Operation not permitted," the file may carry the immutable flag, remove it with sudo chattr -i /etc/hosts, reset, then optionally restore it. See flush DNS on Linux.

Why reset the hosts file?

• Adware / malware cleanup, unwanted software often injects redirect lines (e.g. pointing antivirus or ad domains elsewhere). A reset wipes them.
• Undo broken edits, a malformed or forgotten custom line can send a real site to the wrong IP.
• Clean baseline, start troubleshooting from a known-good file.
• Restore localhost, if the loopback line was deleted, the default brings it back. Related: localhost refused to connect.

If unknown redirects pointed your bank, email, or antivirus domains somewhere unexpected, run a malware scan after resetting, see is editing the hosts file safe?.

Keep a clean hosts file without manual resets

Constantly nuking the file is a blunt tool. A hosts manager like Sleezr keeps your default entries protected, lets you toggle custom domains on and off per project, and flushes DNS automatically, so you rarely need a full reset, and when you do, your real mappings are one click away.

_Last tested: June 2026 on Windows 11, macOS 26 Tahoe and Ubuntu 24.04._

Sources and further reading

• How to reset the Hosts file back to the default (Microsoft Support)
• The hosts file explained (Wikipedia)
• hosts(5) manual page (man7.org)