Lab Information
The system admins team of xFusionCorp Industries has noticed intermittent issues with DNS resolution in several apps . App Server 2 in Stratos Datacenter is having some DNS resolution issues, so we want to add some additional DNS nameservers on this server.
As a temporary fix we have decided to go with Google public DNS (ipv4). Please make appropriate changes on this server.
Lab Solutions
🧭 Part 1: Lab Step-by-Step Guidelines
Objective
Fix DNS resolution on App Server 2 (stapp02) by adding Google Public DNS.
Google DNS servers:
8.8.8.8
8.8.4.4
These must be added to:
/etc/resolv.conf
1️⃣ Login to Jump Host
ssh thor@jump_host.stratos.xfusioncorp.com
Password
mjolnir123
2️⃣ SSH into App Server 2
ssh steve@stapp02
Password
Am3ric@
3️⃣ Switch to Root
sudo -i
4️⃣ Edit the DNS Configuration
Open the file:
vi /etc/resolv.conf
Add the following lines:
nameserver 8.8.8.8
nameserver 8.8.4.4
Save:
ESC
:wq
5️⃣ Verify DNS
Test with:
ping -c 2 google.com
# If ping doesn't found, please run this
yum install -y iputils
If DNS works, it will resolve the IP address.
🧠 Part 2: Simple Explanation (Beginner Friendly)
What DNS does
DNS converts domain names into IP addresses.
Example:
google.com → 142.250.183.238
Without DNS, the system cannot resolve domain names.
Why the server has DNS issues
The lab states:
intermittent DNS resolution issues
This means the current DNS server may be slow or unavailable.
Why we use Google DNS
Google provides reliable public DNS servers:
DNS Server Address
Primary 8.8.8.8
Secondary 8.8.4.4
These are widely used for troubleshooting.
What /etc/resolv.conf does
File:
/etc/resolv.conf
This file tells Linux which DNS servers to query.
Example:
nameserver 8.8.8.8
means:
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