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ntp - NTP Synchronization Monitoring

Note: All examples assume environment variables are set:

export NETSCALER_HOST=192.168.1.10
export NETSCALER_USER=nsroot
export NETSCALER_PASS=nsroot

See Environment Variables for details.

Monitor NTP synchronization status on NetScaler (compatible with check_ntp_peer format).

Basic Usage

Check NTP synchronization

check_netscaler -C ntp

Output (OK):

OK: NTP OK: offset=0.0234s, jitter=12ms, stratum=2, truechimers=4 | offset=0.0234s jitter=12ms stratum=2 truechimers=4

Output (WARNING):

WARNING: offset=0.042s (above 0.03s) | offset=0.042s;0.03;0.05 jitter=15ms stratum=2 truechimers=4

Output (CRITICAL):

CRITICAL: Sync DISABLED

Threshold Format

Thresholds use comma-separated key=value pairs:

o=offset,s=stratum,j=jitter,t=truechimers

Keys:

  • o - Offset in seconds (e.g., 0.03 = 30ms)
  • s - Stratum level (1-16)
  • j - Jitter in milliseconds
  • t - Truechimers count (number of valid peers)

Basic Thresholds

Default check with offset only

check_netscaler -C ntp -w "o=0.03" -c "o=0.05"
  • WARNING if offset > 30ms
  • CRITICAL if offset > 50ms

Check all metrics

check_netscaler -C ntp \
  -w "o=0.03,s=2,j=100,t=3" \
  -c "o=0.05,s=3,j=200,t=2"

Thresholds:

  • Offset: WARN >30ms, CRIT >50ms
  • Stratum: WARN >2, CRIT >3
  • Jitter: WARN >100ms, CRIT >200ms
  • Truechimers: WARN ≤3, CRIT ≤2

NTP Metrics Explained

Offset

Time difference between system clock and NTP time.

  • Typical: <30ms
  • WARNING: 30-50ms
  • CRITICAL: >50ms

Jitter

Variation in offset over time (clock stability).

  • Typical: <50ms
  • WARNING: 50-100ms
  • CRITICAL: >100ms

Stratum

Distance from reference clock (lower is better).

  • 1: Reference clock (GPS, atomic)
  • 2: Primary server (synced to stratum 1)
  • 3+: Secondary servers
  • 16: Unsynchronized

Truechimers

Number of valid NTP peers being used.

  • Peers marked with *, +, or - in ntpq output
  • More truechimers = more reliable synchronization
  • Minimum recommended: 3-4

Advanced Usage

Strict offset monitoring

check_netscaler -C ntp -w "o=0.01" -c "o=0.02"

Very tight offset requirements (10ms/20ms).

Stratum monitoring only

check_netscaler -C ntp -w "s=2" -c "s=3"

Alert if stratum is too high.

Complete monitoring

check_netscaler -C ntp \
  -w "o=0.03,s=2,j=100,t=4" \
  -c "o=0.05,s=3,j=200,t=2"

Synchronization States

Sync Enabled

  • Offset: Time difference in seconds
  • Jitter: Clock stability in milliseconds
  • Stratum: Distance from reference
  • Truechimers: Valid peer count

Sync Disabled or Not Synchronized

  • Returns CRITICAL immediately
  • No metrics available

Performance Data

| offset=<seconds>s;<warn>;<crit> jitter=<ms>ms stratum=<level> truechimers=<count>

Example:

| offset=0.0234s;0.03;0.05 jitter=12ms;100;200 stratum=2;2;3 truechimers=4;3;2

Common Use Cases

1. Basic offset monitoring

check_netscaler -C ntp -w "o=0.03" -c "o=0.05"

2. Recommended full monitoring

check_netscaler -C ntp \
  -w "o=0.03,s=2,j=100,t=3" \
  -c "o=0.05,s=3,j=200,t=2"

3. Strict requirements

check_netscaler -C ntp \
  -w "o=0.01,s=1,j=50,t=4" \
  -c "o=0.02,s=2,j=100,t=3"

Exit Codes

  • 0 (OK) - NTP synchronized, all thresholds within limits
  • 1 (WARNING) - One or more metrics exceed warning threshold
  • 2 (CRITICAL) - Sync disabled/not synchronized OR critical threshold exceeded
  • 3 (UNKNOWN) - Cannot retrieve NTP status or API error

Tips

  • Start with basic offset monitoring: -w "o=0.03" -c "o=0.05"
  • Add jitter and stratum for comprehensive monitoring
  • Truechimers count indicates peer reliability
  • NTP sync must be ENABLED on NetScaler
  • Compatible with check_ntp_peer output format
  • Offset is converted from milliseconds to seconds automatically
  • Use multiple NTP servers (3-4) for best reliability