How to Set Custom NTP Servers on Rocky Linux (EL) and Debian Systems Using Indian NTP Servers

Time synchronization is a critical foundation for any server environment. If your system clock drifts, you risk issues such as:

• SSL/TLS certificate validation errors
• Authentication failures (Kerberos, LDAP, SSO)
• Incorrect log timestamps, making audits impossible
• Cron jobs running at the wrong time
• Database replication errors

To avoid these problems, Linux systems use the Network Time Protocol (NTP). By default, most distributions rely on the global NTP pool project. However, for servers based in India, using National Informatics Centre (NIC) maintained NTP servers gives you more accurate and reliable synchronization:

• samay1.nic.in
• samay2.nic.in

Why Use Indian NTP Servers?

• Lower latency – Much closer geographically than global servers.
• Official Indian Standard Time – Maintained by NIC, aligned with IST.
• Government grade reliability – Ideal for financial, telecom, and compliance systems.
• Fallback independence – Even if international connectivity is poor, NIC servers remain accessible locally.

server vs pool in NTP Configuration

When configuring NTP or Chrony, you’ll encounter two keywords: server and pool. They look similar but behave differently.

The server Directive

• Points directly to one specific NTP server.
• Example:

server samay1.nic.in iburst

• Chrony will keep querying this server unless it becomes unreachable.
• If you list multiple server entries, it will choose the best available.

Use server when:

• You trust specific servers (e.g., NIC-operated samay1/samay2).
• Compliance requires fixed time sources.
• Accuracy and predictability are important (production servers).

The pool Directive

• Refers to a DNS pool that resolves to many rotating servers.
• Example:

pool 2.pool.ntp.org iburst

• Provides automatic redundancy. If one server is down, another is selected.
• Used mostly for general-purpose systems.

Use pool when:

• Running desktops or non-critical servers.
• You want many backup sources without manually listing them.
• You’re outside India without local trusted servers.

Comparison: server vs pool

👉 For Indian servers, use server samay1.nic.in and server samay2.nic.in. Optionally, add one pool entry for global fallback.

Configuring NTP on Rocky Linux (EL Family)

Rocky Linux, AlmaLinux, and RHEL use Chrony as the default NTP client.

Step 1: Install Chrony

sudo dnf install chrony -y

Step 2: Configure Chrony

sudo nano /etc/chrony.conf

Comment out default pool:

# pool 2.centos.pool.ntp.org iburst

Add NIC servers:

server samay1.nic.in iburst
server samay2.nic.in iburst

(Optional: add a fallback)

pool 0.pool.ntp.org iburst

Step 3: Restart and Enable Chrony

sudo systemctl restart chronyd
sudo systemctl enable chronyd

Step 4: Verify

chronyc sources -v
chronyc tracking

Configuring NTP on Debian/Ubuntu

Debian and Ubuntu can use systemd-timesyncd or Chrony.

Option 1: Using systemd-timesyncd

Edit config:

sudo nano /etc/systemd/timesyncd.conf

Add servers:

[Time]
NTP=samay1.nic.in samay2.nic.in

Restart service:

sudo systemctl restart systemd-timesyncd

Verify:

timedatectl status

Option 2: Using Chrony

Install Chrony:

sudo apt update
sudo apt install chrony -y

Edit config:

sudo nano /etc/chrony/chrony.conf

Replace pools with:

server samay1.nic.in iburst
server samay2.nic.in iburst
# Optional fallback
pool 0.pool.ntp.org iburst

Restart Chrony:

sudo systemctl restart chrony
sudo systemctl enable chrony

Verify:

chronyc sources -v
chronyc tracking

Testing NTP Servers

You can test NIC servers before committing changes:

ntpdate -q samay1.nic.in
ntpdate -q samay2.nic.in

A successful response will show the time offset in milliseconds.

Best Practices for Enterprise Servers

• Always configure at least two fixed servers (samay1, samay2).
• Add one pool entry as a global backup.
• Use server for predictable, trusted time sources.
• Use pool only for redundancy on non-critical nodes.
• Monitor drift with:

chronyc tracking

• Ensure all servers in a cluster use the same time sources.

Conclusion

For Indian Rocky Linux and Debian/Ubuntu servers, the best configuration is:

server samay1.nic.in iburst
server samay2.nic.in iburst

This ensures synchronization with official Indian Standard Time (IST) while maintaining accuracy and reliability. Optionally, add a global pool for fallback, but for enterprise systems, trusted fixed servers should always take priority.