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Asked: 2024-09-26T19:27:44+05:30 In:

What service must be restarted after making changes to the /etc/hosts file on an Ubuntu system?

So, I was tinkering around with my Ubuntu system the other day, you know, trying to optimize everything for better performance. I recently started messing with the /etc/hosts file because I read somewhere that it can help with DNS resolution and all that good stuff if you add some entries. I added a few local mappings, hoping it would speed things up a bit, but I also had this nagging feeling that I might be missing a step.

After editing the file, I mean, I did my usual save and close routine, but then I started wondering: what should I do next? Should I just let it be, or is there something I need to restart to ensure that my changes take effect? I considered rebooting my entire machine, but that felt a bit extreme for what seemed like a minor change. Plus, who has the time for a full restart these days, right?

I’ve read somewhere that modifying certain system files requires a restart of specific services, but I couldn’t remember which ones. I know the network service plays a significant role in DNS resolution, so I thought about it, but is it really the right one to restart? I mean, does the /etc/hosts file get reloaded automatically by the system, or is there a particular service that needs a nudge to recognize the updated entries?

Has anyone else dealt with this? What’s the best practice here? Do people usually just restart their networking service to ensure everything’s in sync, or is there another method? I don’t want to mess anything up, especially since my Ubuntu setup is crucial for my projects. Any insights on this would really help me out! Plus, I’m curious about any other tips or tricks you all might have when it comes to editing that file. Thanks!

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    2 Answers



    1. Editing /etc/hosts on Ubuntu

      Editing /etc/hosts on Ubuntu

      Editing the /etc/hosts file is pretty cool! It can indeed help with DNS resolution and map local addresses. After you make changes to the file, there’s usually no need to reboot your entire system, which is great because who has time for that?

      The good news is that most of the time, you don’t need to restart your machine or even the network service for the /etc/hosts changes to take effect. The system reads this file each time it needs to resolve an address, so it’ll pick up your changes pretty quickly.

      However, if you want to be extra sure everything is in sync, you could restart the networking service. It doesn’t hurt to do so, and it’s not too hard. You can run the following command in your terminal:

      sudo systemctl restart NetworkManager

      Another option is to flush the DNS cache if your setup uses one, though Ubuntu typically doesn’t cache DNS entries like some other operating systems do. If you’re using systemd-resolved, you can run:

      sudo systemd-resolve --flush-caches

      As for tips on editing /etc/hosts, it’s good to keep a backup before making changes, just in case something goes wrong. You can easily copy the original file by:

      sudo cp /etc/hosts /etc/hosts.backup

      Lastly, if you mess things up a bit, don’t panic! Just restore the backup, and you should be back to normal in no time.

      Hope this helps you out! Good luck with your Ubuntu tinkering!




    2. Editing /etc/hosts in Ubuntu

      After you make changes to the /etc/hosts file on your Ubuntu system, there’s no need for a full reboot. The /etc/hosts file is consulted by the system as part of the DNS resolution process, and changes to it actually take effect immediately. This means that most applications will reflect the new mappings without any additional steps. However, if you have services running that have established connections based on old DNS entries or if you are running certain applications that cache DNS lookups, you might want to restart those specific services or applications to ensure they pick up the new mappings. For networking-related services, you can use the command sudo systemctl restart NetworkManager to restart the network service if you think it’s necessary.

      In general, it’s a good idea to keep in mind that many applications handle DNS lookups independently. For better control over DNS caching, you might consider installing and configuring a local caching DNS resolver like dnsmasq. This can provide greater flexibility in DNS management for your projects. When editing the /etc/hosts file, ensure you format entries correctly: IP address followed by the hostname, and make separate lines for each entry. Avoid adding comments or special characters that might disrupt the parsing of the file. Overall, keeping it clean and organized will help you in troubleshooting and maintaining performance.


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