Time Synchronization FAQ

Frequently asked questions about NTP and time synchronization services

Time Synchronization FAQ

This guide answers common questions about time synchronization, NTP servers, and best practices for keeping your systems accurately synchronized.

General Questions

What is NTP?

NTP (Network Time Protocol) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks. It provides accurate time synchronization with millisecond precision.

Why is accurate time important?

Accurate time synchronization is crucial for:

• Security: Certificate validation, authentication logs, and security protocols
• Distributed Systems: Database consistency, transaction ordering, and coordination
• Compliance: Regulatory requirements for audit trails and timestamps
• Debugging: Correlating logs across multiple systems
• Financial Transactions: Precise timing for trading and payment processing

What’s the difference between NTP and Roughtime?

• NTP: Traditional protocol providing high precision time synchronization
• Roughtime: Modern, secure protocol with cryptographic guarantees against network attacks
• Best Practice: Use both - Roughtime for security, NTP for precision

Using Hixbe NTP Servers

How do I configure my system to use time.hixbe.com?

Linux (systemd):

# Edit /etc/systemd/timesyncd.conf
sudo nano /etc/systemd/timesyncd.conf

# Add or modify:
NTP=time.hixbe.com
FallbackNTP=ntp.ubuntu.com

# Restart the service
sudo systemctl restart systemd-timesyncd

Linux (chrony):

# Edit /etc/chrony/chrony.conf
sudo nano /etc/chrony/chrony.conf

# Add:
server time.hixbe.com iburst

# Restart chrony
sudo systemctl restart chrony

Windows:

# Open PowerShell as Administrator
w32tm /config /manualpeerlist:time.hixbe.com /syncfromflags:manual /reliable:yes /update
w32tm /resync

What ports need to be open?

• NTP: UDP port 123
• Roughtime: TCP port 2002

Is there any rate limiting?

Our NTP servers are provided free of charge with reasonable usage limits. For high-volume applications, consider using multiple NTP servers or implementing local NTP servers.

Troubleshooting

My system isn’t synchronizing

Check firewall settings:

# Linux
sudo ufw allow 123/udp
# or
sudo iptables -A INPUT -p udp --dport 123 -j ACCEPT

Verify NTP service status:

# systemd
systemctl status systemd-timesyncd

# chrony
chronyc sources
chronyc tracking

Check time difference:

# Quick check
ntpdate -q time.hixbe.com

I’m getting “no server suitable for synchronization”

This usually means:

1. Firewall blocking NTP traffic
2. Incorrect server configuration
3. Network connectivity issues
4. NTP service not running

How do I verify synchronization is working?

Linux:

timedatectl status
ntpstat

Windows:

w32tm /query /status

Check offset:

# Using ntpdate
ntpdate -q time.hixbe.com

# Using chronyc
chronyc tracking

Best Practices

Redundancy

Always configure multiple NTP servers:

# /etc/systemd/timesyncd.conf
NTP=time.hixbe.com ntp.ubuntu.com time.nist.gov

Monitoring

Monitor your time synchronization:

# Check offset regularly
chronyc tracking | grep "System time"

# Alert if offset > 100ms
#!/bin/bash
OFFSET=$(chronyc tracking | grep "System time" | awk '{print $4}')
if (( $(echo "$OFFSET > 0.1" | bc -l) )); then
    echo "Time offset too high: $OFFSET seconds"
fi

Security Considerations

1. Use authenticated NTP when possible (NTPv4 with autokey)
2. Implement Roughtime for cryptographic security
3. Monitor for time jumps that could indicate attacks
4. Use local NTP servers for internal networks

Advanced Configuration

NTP Pool Configuration

For high availability, use NTP pools:

# /etc/ntp.conf
server 0.pool.ntp.org
server 1.pool.ntp.org
server time.hixbe.com

Custom NTP Server Setup

If you need your own NTP server:

# Install NTP
sudo apt install ntp

# Configure upstream servers
# /etc/ntp.conf
server time.hixbe.com prefer
server ntp.ubuntu.com

# Configure as server
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
restrict 127.0.0.1
restrict -6 ::1

Common Issues and Solutions

Large time jumps

Cause: System clock was significantly off Solution: Use ntpd instead of ntpdate for gradual correction

NTP socket in use

Cause: Multiple NTP services running Solution:

sudo systemctl stop ntp
sudo systemctl disable ntp
sudo systemctl enable systemd-timesyncd

DNS resolution failures

Cause: DNS issues preventing server lookup Solution: Use IP addresses directly or fix DNS configuration

Performance Tuning

For low-latency applications

# /etc/chrony/chrony.conf
server time.hixbe.com iburst minpoll 4 maxpoll 6
makestep 0.1 3

For power-constrained devices

# Less frequent polling
server time.hixbe.com minpoll 8 maxpoll 12

Monitoring and Alerting

NTP Monitoring Script

#!/bin/bash
# ntp-monitor.sh

SERVERS=("time.hixbe.com" "ntp.ubuntu.com")
THRESHOLD=0.5  # seconds

for server in "${SERVERS[@]}"; do
    if ntpdate -q "$server" >/dev/null 2>&1; then
        offset=$(ntpdate -q "$server" 2>/dev/null | tail -1 | awk '{print $9}')
        if (( $(echo "${offset#-} > $THRESHOLD" | bc -l) )); then
            echo "WARNING: High offset $offset seconds from $server"
        else
            echo "OK: $server offset $offset seconds"
        fi
    else
        echo "ERROR: Cannot reach $server"
    fi
done

Support

If you’re still having issues:

1. Check our NTP Servers documentation
2. Visit the NTP Pool status page
3. Contact support at [e-mail] with:
   • Your operating system and version
   • NTP client configuration
   • Error messages
   • Network setup details

Related Resources

NTP Documentation

Complete NTP server documentation

NTP Pool Project

Join the NTP Pool project

Chrony Documentation

Advanced NTP client documentation

Roughtime Specification

Roughtime protocol details