Setting Up DNS in Alpine Linux: No More Network Headaches

I’ll show you how to fix DNS problems in Alpine Linux. Trust me, I’ve spent way too many hours fighting with DNS issues. This stuff can be tricky, but I’ll walk you through it step by step.

Introduction

So here’s the thing - DNS makes your computer find websites by their names instead of remembering crazy IP numbers. Alpine Linux does this differently than other systems. It doesn’t use that systemd thing. Instead, it keeps things simple with basic config files.

I struggled with this when I first started using Alpine. The internet would work with IP addresses but not website names. Pretty frustrating stuff.

Why You Need This

• Your browser can find websites properly
• Package downloads work without errors
• Network problems become way easier to fix
• You’ll stop getting weird connection failures

Prerequisites

You’ll need these things first:

• Root access to your Alpine Linux system
• A text editor like nano or vim
• Basic terminal knowledge
• Working internet connection (at least with IP addresses)

What we’re doing: Let’s check if your network actually works before we fix DNS.

# See what network stuff you have
ip addr show

# Test if internet works with IP numbers
ping -c 3 8.8.8.8

Code explanation:

• ip addr show: Shows all your network connections and their IP addresses
• ping -c 3 8.8.8.8: Sends 3 test packets to Google’s DNS server
• -c 3: Stops after 3 tries so it doesn’t run forever

How DNS Works in Alpine Linux

Alpine Linux uses a few different files to figure out where websites are. It’s actually pretty simple once you get it.

The Important Files

• /etc/resolv.conf: Main DNS config file
• /etc/hosts: Local website mappings
• /etc/nsswitch.conf: How the system looks things up
• openresolv: Advanced DNS management tool

How Your Computer Finds Websites

1. Checks /etc/hosts for local entries first
2. Asks DNS servers in /etc/resolv.conf
3. Uses search domains for short names
4. Returns the IP address or gives up

Method 1: Quick DNS Fix

Step 1: Edit the Main DNS File

This is the easiest way to get DNS working. I use this method most of the time.

What we’re doing: We’ll backup your current DNS settings and then fix them.

# Make a backup so we can undo this later
sudo cp /etc/resolv.conf /etc/resolv.conf.backup

# Open the DNS config file
sudo nano /etc/resolv.conf

Code explanation:

• sudo cp /etc/resolv.conf /etc/resolv.conf.backup: Makes a safety copy
• sudo nano /etc/resolv.conf: Opens the DNS file in nano editor
• sudo: Needed because this file belongs to root

What we’re doing: Adding good DNS servers that actually work reliably.

Replace everything in /etc/resolv.conf with this:

# Google's DNS servers - they're pretty fast
nameserver 8.8.8.8
nameserver 8.8.4.4

# Cloudflare DNS - also good (you can use this instead)
# nameserver 1.1.1.1
# nameserver 1.0.0.1

# Search domain for short names (change this to your domain)
search example.com

# Make DNS faster by timing out quicker
options timeout:2
options attempts:3

Configuration explanation:

• nameserver 8.8.8.8: Primary DNS server (Google’s)
• nameserver 8.8.4.4: Backup DNS server in case the first one fails
• search example.com: Domain to add to short names
• options timeout:2: Don’t wait more than 2 seconds for a response
• options attempts:3: Try 3 times before giving up

Step 2: Test That It Works

What we’re doing: Making sure our DNS changes actually work.

# Test basic website lookup
nslookup google.com

# Try a different testing tool
dig google.com

# Test with a specific DNS server
nslookup google.com 8.8.8.8

Code explanation:

• nslookup google.com: Asks DNS to find google.com’s IP address
• dig google.com: Another way to test DNS (gives more info)
• nslookup google.com 8.8.8.8: Tests using Google’s DNS server directly

Expected Output:

Server:    8.8.8.8
Address:   8.8.8.8#53

Non-authoritative answer:
Name:      google.com
Address:   142.250.185.46

What this means: DNS is working! The server found google.com and gave us its IP address.

Step 3: Stop Other Programs from Breaking This

What we’re doing: Some programs like to “help” by changing your DNS settings. We’ll stop them.

# Method 1: Make the file unchangeable
sudo chattr +i /etc/resolv.conf

# Method 2: Use a custom file (if method 1 doesn't work)
sudo mv /etc/resolv.conf /etc/resolv.conf.orig
sudo ln -s /etc/resolv.conf.custom /etc/resolv.conf

Code explanation:

• sudo chattr +i /etc/resolv.conf: Makes the file unchangeable (immutable)
• sudo mv /etc/resolv.conf /etc/resolv.conf.orig: Renames the original file
• sudo ln -s: Creates a link to a custom DNS file

Method 2: Network Interface DNS Settings

Using Network Config Files

What we’re doing: Setting up DNS that sticks around when you restart the network.

# Edit the network config file
sudo nano /etc/network/interfaces

Code explanation:

• sudo nano /etc/network/interfaces: Opens the file where network settings live

What we’re doing: Adding DNS settings right into your network configuration.

Add this to your interface settings:

# For DHCP (automatic IP) with custom DNS
auto eth0
iface eth0 inet dhcp
    dns-nameservers 8.8.8.8 8.8.4.4
    dns-search example.com
    dns-domain example.com

# For static IP with custom DNS
auto eth0
iface eth0 inet static
    address 192.168.1.100
    netmask 255.255.255.0
    gateway 192.168.1.1
    dns-nameservers 8.8.8.8 8.8.4.4
    dns-search example.com

Configuration explanation:

• auto eth0: Starts this network connection automatically
• iface eth0 inet dhcp: Uses automatic IP assignment
• dns-nameservers 8.8.8.8 8.8.4.4: Sets custom DNS servers
• dns-search example.com: Domain to search for short names
• inet static: Alternative for manual IP setup

Restart Your Network

What we’re doing: Applying our new settings by restarting the network.

# Restart all network stuff
sudo service networking restart

# Or restart just one connection
sudo ifdown eth0 && sudo ifup eth0

# Check if it worked
cat /etc/resolv.conf

Code explanation:

• sudo service networking restart: Restarts all network connections
• sudo ifdown eth0: Turns off the eth0 connection
• sudo ifup eth0: Turns on the eth0 connection with new settings
• cat /etc/resolv.conf: Shows what’s in the DNS file now

Stop DHCP from Messing Things Up

What we’re doing: Making the DHCP client use our DNS servers instead of what the router gives us.

# Edit DHCP client settings
sudo nano /etc/dhcpcd.conf

Code explanation:

• sudo nano /etc/dhcpcd.conf: Opens the DHCP client config file

What we’re doing: Telling DHCP to use our DNS servers no matter what.

Add these lines:

# Use our DNS servers instead of router's
static domain_name_servers=8.8.8.8 8.8.4.4

# Don't let DHCP change our DNS file
nohook resolv.conf

Configuration explanation:

• static domain_name_servers=8.8.8.8 8.8.4.4: Forces use of our DNS servers
• nohook resolv.conf: Stops DHCP from changing /etc/resolv.conf

Method 3: Advanced DNS Setup

Using openresolv

What we’re doing: Installing a tool that handles multiple network connections with different DNS servers.

# Install the openresolv package
sudo apk add openresolv

# Set up DNS for a specific network connection
sudo resolvconf -a eth0 << EOF
nameserver 8.8.8.8
nameserver 8.8.4.4
search example.com
EOF

Code explanation:

• sudo apk add openresolv: Downloads and installs the openresolv tool
• sudo resolvconf -a eth0: Adds DNS config for the eth0 connection
• << EOF ... EOF: Feeds multiple lines to the command

What we’re doing: Managing DNS settings for different connections.

# See all DNS settings
resolvconf -l

# Remove DNS settings for a connection
resolvconf -d eth0

Code explanation:

• resolvconf -l: Lists all DNS configurations
• resolvconf -d eth0: Deletes DNS settings for eth0

Different DNS for Different Networks

What we’re doing: Setting up different DNS servers for WiFi vs Ethernet. This is pretty cool.

# WiFi gets Cloudflare DNS
sudo resolvconf -a wlan0 << EOF
nameserver 1.1.1.1
nameserver 1.0.0.1
EOF

# Ethernet gets Google DNS
sudo resolvconf -a eth0 << EOF
nameserver 8.8.8.8
nameserver 8.8.4.4
EOF

Code explanation:

• resolvconf -a wlan0: Sets DNS just for WiFi
• resolvconf -a eth0: Sets DNS just for Ethernet
• Different DNS servers can be faster for different connections

Secure DNS Setup

DNS over HTTPS

What we’re doing: Encrypting DNS requests so nobody can spy on what websites you visit.

# Install cloudflared
sudo apk add cloudflared

# Make config directory
sudo mkdir -p /etc/cloudflared
sudo nano /etc/cloudflared/config.yml

Code explanation:

• sudo apk add cloudflared: Installs Cloudflare’s DNS tool
• sudo mkdir -p /etc/cloudflared: Creates the config folder
• -p: Creates parent folders if needed

What we’re doing: Setting up encrypted DNS that runs locally.

Add this to /etc/cloudflared/config.yml:

# Turn on DNS proxy mode
proxy-dns: true

# Local port to listen on
proxy-dns-port: 5053

# Encrypted DNS servers
proxy-dns-upstream:
  - https://1.1.1.1/dns-query
  - https://1.0.0.1/dns-query

Configuration explanation:

• proxy-dns: true: Turns on DNS proxy mode
• proxy-dns-port: 5053: Port where the proxy listens
• proxy-dns-upstream: HTTPS URLs for encrypted DNS

What we’re doing: Starting the encrypted DNS service.

# Start cloudflared at boot
sudo rc-update add cloudflared

# Start it now
sudo service cloudflared start

# Point system to our encrypted DNS
echo "nameserver 127.0.0.1" | sudo tee /etc/resolv.conf

Code explanation:

• sudo rc-update add cloudflared: Makes it start automatically
• sudo service cloudflared start: Starts the service now
• echo "nameserver 127.0.0.1": Points DNS to our local encrypted proxy

Testing Your DNS

Basic Tests

What we’re doing: Making sure everything actually works like it should.

# Basic website lookup
nslookup google.com

# More detailed info
dig google.com

# Reverse lookup (IP to name)
nslookup 8.8.8.8

# Check different record types
dig google.com MX
dig google.com TXT

Code explanation:

• nslookup google.com: Basic DNS test
• dig google.com: More detailed DNS info
• nslookup 8.8.8.8: Finds domain name for IP address
• dig google.com MX: Looks up mail server records
• dig google.com TXT: Looks up text records

Speed Tests

What we’re doing: Figuring out which DNS servers are fastest for you.

# Install testing tools
sudo apk add bind-tools

# Time how long DNS takes
time nslookup google.com

# Test different DNS servers
for dns in 8.8.8.8 1.1.1.1 208.67.222.222; do
    echo "Testing DNS server: $dns"
    time nslookup google.com $dns
done

Code explanation:

• sudo apk add bind-tools: Installs DNS testing tools
• time nslookup google.com: Shows how long the lookup takes
• for dns in ...: Tests multiple DNS servers
• time nslookup google.com $dns: Times query to specific server

Fixing Common Problems

Problem 1: DNS Doesn’t Work at All

What’s wrong: You can ping IP addresses but can’t reach websites by name.

What we’re doing: Step by step troubleshooting to find the issue.

# Check what DNS servers you're using
cat /etc/resolv.conf

# Test if you can reach the DNS server
ping 8.8.8.8

# Check your network routing
ip route show

# Look for DNS programs running
ps aux | grep -E "(unbound|dnsmasq)"

Code explanation:

• cat /etc/resolv.conf: Shows your current DNS settings
• ping 8.8.8.8: Tests if you can reach Google’s DNS server
• ip route show: Shows how your network traffic gets routed
• ps aux | grep -E "(unbound|dnsmasq)": Looks for DNS programs

Problem 2: DNS is Really Slow

What’s wrong: Websites take forever to load because DNS lookups are slow.

What we’re doing: Testing different servers and setting up local caching.

# Compare different DNS servers
time nslookup google.com 8.8.8.8
time nslookup google.com 1.1.1.1

# Install local DNS cache
sudo apk add dnsmasq

# Set up caching
sudo nano /etc/dnsmasq.conf

Code explanation:

• time nslookup: Shows how long each DNS server takes
• sudo apk add dnsmasq: Installs a local DNS cache
• Local cache makes repeated lookups much faster

What we’re doing: Setting up dnsmasq to cache DNS queries locally.

Add this to /etc/dnsmasq.conf:

# How many DNS queries to remember
cache-size=1000

# DNS servers to ask when cache misses
server=8.8.8.8
server=8.8.4.4

# Only listen locally for security
listen-address=127.0.0.1

Configuration explanation:

• cache-size=1000: Remembers 1000 recent DNS queries
• server=8.8.8.8: Upstream server when cache doesn’t have the answer
• listen-address=127.0.0.1: Only accepts queries from local machine

Problem 3: Settings Keep Getting Reset

What’s wrong: Your DNS settings work but get changed back after reboot.

What we’re doing: Making DNS settings permanent.

# Check if resolv.conf is being overwritten
ls -la /etc/resolv.conf

# Stop DHCP from changing DNS
sudo nano /etc/dhcpcd.conf

Code explanation:

• ls -la /etc/resolv.conf: Shows if the file is a link to something else
• DHCP often overwrites DNS settings with router defaults

Add this line to /etc/dhcpcd.conf: nohook resolv.conf

What this does: Stops DHCP from messing with your DNS settings.

Speed Things Up with Caching

Set Up DNS Caching

What we’re doing: Making a local DNS cache so repeat lookups are instant.

# Install dnsmasq
sudo apk add dnsmasq

# Configure it
sudo nano /etc/dnsmasq.conf

Code explanation:

• Local cache stores recent DNS results in memory
• Second time you visit a site, DNS is instant

What we’re doing: Configuring dnsmasq for best performance.

Add this to /etc/dnsmasq.conf:

# Cache 1000 recent DNS queries
cache-size=1000

# Use these DNS servers for new queries
server=8.8.8.8
server=8.8.4.4

# Security - only local connections
listen-address=127.0.0.1

# Don't read hosts file
no-hosts

# Log queries for debugging
log-queries

Configuration explanation:

• cache-size=1000: Adjust this based on how much RAM you have
• server=: Use multiple servers for backup
• listen-address=127.0.0.1: Prevents outside access
• log-queries: Helps when things go wrong

What we’re doing: Starting the cache and pointing DNS to it.

# Start dnsmasq at boot
sudo rc-update add dnsmasq

# Start it now
sudo service dnsmasq start

# Use local cache for DNS
echo "nameserver 127.0.0.1" | sudo tee /etc/resolv.conf

Code explanation:

• sudo rc-update add dnsmasq: Makes it start automatically
• echo "nameserver 127.0.0.1": All DNS goes through local cache
• Cache forwards unknown queries to upstream servers

Best Practices That Actually Work

Use Multiple DNS Servers

What we’re doing: Setting up backup DNS servers so things don’t break.

# Edit DNS config
sudo nano /etc/resolv.conf

Add multiple servers:

# Primary DNS (usually fastest)
nameserver 1.1.1.1

# Backup DNS
nameserver 8.8.8.8

# Last resort (your router)
nameserver 192.168.1.1

# Speed up failover
options timeout:1
options attempts:2
options rotate

Configuration explanation:

• Multiple servers mean automatic backup if one fails
• timeout:1: Fail over faster
• attempts:2: Don’t try too many times
• rotate: Spreads load across servers

Monitor DNS Health

What we’re doing: Setting up automatic checking so you know when DNS breaks.

# Create monitoring script
sudo nano /usr/local/bin/dns-monitor.sh

Code explanation:

• Automatic monitoring catches problems before you notice them
• Script runs regularly to test DNS

#!/bin/sh
# Check if DNS servers are working

# Where to log results
LOGFILE="/var/log/dns-monitor.log"

# DNS servers to test
DNSSERVERS="8.8.8.8 1.1.1.1"

# Test each server
for server in $DNSSERVERS; do
    if ! nslookup google.com $server > /dev/null 2>&1; then
        echo "$(date): DNS server $server failed" >> $LOGFILE
    fi
done

Code explanation:

• #!/bin/sh: Use basic shell for compatibility
• LOGFILE="/var/log/dns-monitor.log": Where to save results
• for server in $DNSSERVERS: Tests each DNS server
• > /dev/null 2>&1: Hides output, just checks if it works

What we’re doing: Making the script run automatically.

# Make it executable
sudo chmod +x /usr/local/bin/dns-monitor.sh

# Run every 5 minutes
echo "*/5 * * * * /usr/local/bin/dns-monitor.sh" | sudo crontab -

Code explanation:

• sudo chmod +x: Makes the script runnable
• */5 * * * *: Cron schedule meaning “every 5 minutes”
• sudo crontab -: Adds the job to root’s schedule

Real-World Examples

Corporate Network

What we’re doing: Setting up DNS for office networks with internal servers.

# Install dnsmasq for smart routing
sudo apk add dnsmasq

# Configure split DNS
sudo nano /etc/dnsmasq.conf

Code explanation:

• Split DNS sends internal domains to company servers
• External domains go to public DNS

# Company stuff goes to internal DNS
server=/company.local/192.168.1.10

# Everything else goes to public DNS
server=8.8.8.8
server=8.8.4.4

# VPN domains go to VPN DNS
server=/vpn.company.com/10.0.0.1

Configuration explanation:

• /company.local/192.168.1.10: Internal domain routing
• server=8.8.8.8: Public DNS for everything else
• Lets you access both internal and external sites

Development Setup

What we’re doing: Setting up local development domains.

# Edit hosts file for local development
sudo nano /etc/hosts

Add local mappings:

# Local development sites
127.0.0.1 app.local
127.0.0.1 api.local
127.0.0.1 db.local

Configuration explanation:

• Maps development domains to localhost
• Use real domain names while developing
• Works without internet connection

Wrapping Up

You just learned how to:

• Fix DNS problems that stop websites from loading
• Set up multiple DNS servers for backup
• Make DNS faster with local caching
• Stop other programs from breaking your settings

That’s it! You now know how to handle DNS in Alpine Linux. This stuff has saved me tons of time debugging network problems. I use local caching on all my systems now - it makes everything feel snappier.

These methods work great and I’ve used them on everything from tiny IoT devices to big servers. DNS problems used to drive me crazy, but now they’re no big deal.