Are you getting the following error message when you try to run apt upgrade, apt update or apt install command ?

Err:1 [ Ссылка ] focal InRelease
Temporary failure resolving 'us.archive.ubuntu.com'
Err:2 [ Ссылка ] focal-security InRelease
Temporary failure resolving 'security.ubuntu.com'
Err:3 [ Ссылка ] focal-updates InRelease
Temporary failure resolving 'us.archive.ubuntu.com'
Err:4 [ Ссылка ] focal InRelease
Temporary failure resolving 'download.docker.com'
Err:5 [ Ссылка ] focal-backports InRelease
Temporary failure resolving 'us.archive.ubuntu.com'
Reading package lists... Done
Building dependency tree
Reading state information... Done
101 packages can be upgraded. Run 'apt list --upgradable' to see them.
W: Failed to fetch [ Ссылка ] Temporary failure resolving 'us.archive.ubuntu.com'
W: Failed to fetch [ Ссылка ] Temporary failure resolving 'us.archive.ubuntu.com'
W: Failed to fetch [ Ссылка ] Temporary failure resolving 'us.archive.ubuntu.com'
W: Failed to fetch [ Ссылка ] Temporary failure resolving 'security.ubuntu.com'
W: Failed to fetch [ Ссылка ] Temporary failure resolving 'download.docker.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.

What the error means
The error messages you're seeing indicate that your system is unable to connect to the specified package repositories to update the package lists. The most common reason for this issue is a problem with your network or DNS configuration.

Here are some steps you can take to diagnose and resolve the issue:
ping 8.8.8.8
ufw status


Solution
This is how you can resolve it.

1) Open /etc/resolv.conf using text editor
nano /etc/resolv.conf

2) Add a nameserver facing the Google DNS server like this.
nameserver 8.8.8.8
OR
nameserver 8.8.4.4

3) Save and exit

4) Try running apt update again.
apt update

Reason
The original content of /etc/resolv.conf with "nameserver 127.0.0.53" suggests that your system was configured to use a local DNS resolver. This typically indicates that your system is using systemd-resolved, a local DNS resolver service that listens on 127.0.0.53 by default.

While systemd-resolved can work well, issues can sometimes arise, particularly if it's not properly configured or if there are issues with the local DNS resolver itself. When you changed the nameserver to "8.8.8.8," you switched to using Google's public DNS server, which is a well-known and reliable DNS service.

What is /etc/resolv.conf
The /etc/resolv.conf file is a critical configuration file on Unix-like operating systems, including Linux. It is used to configure the DNS (Domain Name System) resolver library, which is responsible for resolving domain names to IP addresses. The DNS resolver library is used by the operating system and applications to translate human-friendly domain names (e.g., www.example.com) into IP addresses (e.g., 203.0.113.1) that computers use to communicate over the internet.

apt update
apt install nfs-common -y open-iscsi
apt upgrade -y

#linux #ubuntu

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