When dealing with virtual machines, clock drift becomes a significant concern due to the nature of virtualized hardware. The standard NTPD configuration often proves insufficient for maintaining precise time synchronization in such environments.

The primary parameters we need to adjust in /etc/ntp.conf are:

# Force more frequent synchronization
server ntp.example.com minpoll 4 maxpoll 4 iburst
tinker panic 0

Let's examine each component in detail:

# The server directive with poll adjustments
server 0.pool.ntp.org minpoll 4 maxpoll 4 iburst
server 1.pool.ntp.org minpoll 4 maxpoll 4 iburst
server 2.pool.ntp.org minpoll 4 maxpoll 4 iburst
server 3.pool.ntp.org minpoll 4 maxpoll 4 iburst

# Disable panic threshold
tinker panic 0

# Reduce the minimum adjustment threshold
tinker step 0.1
tinker stepout 1

For virtual environments, additional measures are often necessary:

# Enable kernel discipline
disable kernel

# Set tighter synchronization parameters
tos maxdist 30
tos mindist 0.001
tos maxclock 100

After implementing these changes, verify with:

ntpq -pn
ntpstat
watch -n 1 ntptime

For extreme cases, consider switching to chrony which handles VM clock drift better:

pool ntp.example.com iburst maxsamples 8
makestep 1.0 3
driftfile /var/lib/chrony/drift
rtcsync

Be aware that more frequent synchronization increases:

• Network traffic
• CPU usage
• Potential for NTP server abuse

When working with virtual machines, particularly in cloud environments, clock drift becomes a significant issue. The virtualized hardware clock tends to drift much faster than physical hardware - sometimes several milliseconds per minute. Standard NTPD configurations aren't designed to handle this aggressive drift pattern.

By default, ntpd:

• Uses a minpoll of 6 (64 seconds) and maxpoll of 10 (1024 seconds)
• Gradually adjusts the clock to avoid sudden jumps
• May ignore small time differences to maintain stability

The key configuration parameters we'll focus on:

# /etc/ntp.conf
tinker panic 0      # Disable panic threshold
tinker step 0.1     # Allow smaller time adjustments

To make ntpd adjust the system clock more aggressively:

# /etc/ntp.conf
server ntp.example.com iburst minpoll 4 maxpoll 4
driftfile /var/lib/ntp/drift
tinker allan 0
tinker dispersion 0.1
tinker step 0.01

For VMs, we need to combine NTPD with other tools:

# Install additional tools
sudo apt-get install chrony

# Chrony configuration (/etc/chrony/chrony.conf)
makestep 0.1 3
local stratum 10

Check the adjustment frequency:

ntpq -p
ntpstat
grep adjust /var/log/syslog

Look for lines containing "time reset" or "step time" in your system logs to confirm the increased adjustment frequency.

For systems with systemd:

sudo timedatectl set-ntp false
sudo timedatectl set-ntp true
sudo systemctl restart ntp

This forces an immediate resync and can help when drift becomes excessive.