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The nsd-control stats command shows a number of statistic counters. Statistics must be enabled at compile time with --enable-bind8-stats or --enable-zone-stats.

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Viewing Statistics

# Display statistics and reset counters
nsd-control stats

# Display statistics without resetting counters
nsd-control stats_noreset

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Server Statistics

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num.queries

Total number of queries received (the tls, tcp and udp queries added up).Type: Counter
Prometheus: nsd_queries_total
num.queries=1234567

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serverX.queries

Number of queries handled by the server process. The number of server processes is set with the config statement server-count.Type: Counter
Prometheus: nsd_queries_total{server="X"}
server0.queries=617284
server1.queries=617283

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num.type.X

Number of queries with this query type.Type: Counter
Prometheus: nsd_queries_by_type_total{type="TYPE"}Common types:
  • num.type.A - IPv4 address queries
  • num.type.AAAA - IPv6 address queries
  • num.type.MX - Mail exchange queries
  • num.type.NS - Name server queries
  • num.type.SOA - Start of authority queries
  • num.type.TXT - Text record queries
  • num.type.CNAME - Canonical name queries
  • num.type.DNSKEY - DNSSEC public key queries
  • num.type.DS - Delegation signer queries
  • num.type.RRSIG - DNSSEC signature queries
  • num.type.NSEC - DNSSEC next secure queries
  • num.type.NSEC3 - DNSSEC next secure v3 queries
num.type.A=850000
num.type.AAAA=250000
num.type.MX=50000

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num.class.X

Number of queries with this query class.Type: Counter
Prometheus: nsd_queries_by_class_total{class="CLASS"}Classes:
  • num.class.IN - Internet class (most common)
  • num.class.CH - Chaos class
  • num.class.HS - Hesiod class
  • num.class.ANY - Any class
num.class.IN=1234567
num.class.CH=123

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num.opcode.X

Number of queries with this opcode.Type: Counter
Prometheus: nsd_queries_by_opcode_total{opcode="OPCODE"}Opcodes:
  • num.opcode.QUERY - Standard query (most common)
  • num.opcode.IQUERY - Inverse query (obsolete)
  • num.opcode.STATUS - Server status request
  • num.opcode.NOTIFY - Zone change notification
  • num.opcode.UPDATE - Dynamic update
num.opcode.QUERY=1234000
num.opcode.NOTIFY=567

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num.rcode.X

Number of answers that carried this return code.Type: Counter
Prometheus: nsd_queries_by_rcode_total{rcode="RCODE"}Return codes:
  • num.rcode.NOERROR - Successful query
  • num.rcode.FORMERR - Format error
  • num.rcode.SERVFAIL - Server failure
  • num.rcode.NXDOMAIN - Non-existent domain
  • num.rcode.NOTIMP - Not implemented
  • num.rcode.REFUSED - Query refused
  • num.rcode.YXDOMAIN - Name exists when it should not
  • num.rcode.YXRRSET - RR set exists when it should not
  • num.rcode.NXRRSET - RR set that should exist does not
  • num.rcode.NOTAUTH - Not authoritative
  • num.rcode.NOTZONE - Name not in zone
  • num.rcode.BADVERS - Bad EDNS version
num.rcode.NOERROR=900000
num.rcode.NXDOMAIN=300000
num.rcode.SERVFAIL=1234

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num.udp

Number of queries over UDP ip4.Type: Counter
Prometheus: nsd_queries_by_transport_total{transport="udp"}

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num.udp6

Number of queries over UDP ip6.Type: Counter
Prometheus: nsd_queries_by_transport_total{transport="udp6"}

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num.tcp

Number of connections over TCP ip4.Type: Counter
Prometheus: nsd_connections_total{transport="tcp"}

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num.tcp6

Number of connections over TCP ip6.Type: Counter
Prometheus: nsd_connections_total{transport="tcp6"}

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num.tls

Number of connections over TLS ip4. TLS queries are not part of num.tcp.Type: Counter
Prometheus: nsd_connections_total{transport="tls"}

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num.tls6

Number of connections over TLS ip6. TLS queries are not part of num.tcp6.Type: Counter
Prometheus: nsd_connections_total{transport="tls6"}
num.udp=900000
num.udp6=250000
num.tcp=50000
num.tcp6=10000
num.tls=5000
num.tls6=2000

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num.edns

Number of queries with EDNS OPT.Type: Counter
Prometheus: nsd_queries_with_edns_total

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num.ednserr

Number of queries which failed EDNS parse.Type: Counter
Prometheus: nsd_queries_with_edns_failed_total
num.edns=500000
num.ednserr=123

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num.raxfr

Number of AXFR requests from clients (that got served with reply).Type: Counter
Prometheus: nsd_xfr_requests_served_total{xfrtype="AXFR"}

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num.rixfr

Number of IXFR requests from clients (that got served with reply).Type: Counter
Prometheus: nsd_xfr_requests_served_total{xfrtype="IXFR"}
num.raxfr=45
num.rixfr=234

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num.dropped

Number of queries that were dropped because they failed sanity check.Type: Counter
Prometheus: nsd_queries_dropped_total

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num.rxerr

Number of queries for which the receive failed.Type: Counter
Prometheus: nsd_queries_rx_failed_total

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num.txerr

Number of answers for which the transmit failed.Type: Counter
Prometheus: nsd_answers_tx_failed_total

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num.truncated

Number of answers with TC flag set.Type: Counter
Prometheus: nsd_answers_truncated_total

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num.answer_wo_aa

Number of answers with NOERROR rcode and without AA flag, this includes the referrals.Type: Counter
Prometheus: nsd_answers_without_aa_total
num.dropped=567
num.rxerr=12
num.txerr=8
num.truncated=1234
num.answer_wo_aa=456

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Time Statistics

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time.boot

Uptime in seconds since the server was started. With fractional seconds.Type: Counter
Prometheus: nsd_time_up_seconds_total
time.boot=86400.123456

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time.elapsed

Time since the last stats report, in seconds. With fractional seconds. Can be zero if polled quickly and the previous stats command resets the counters, so that the next gets a fully zero, and zero elapsed time, report.Type: Gauge
Prometheus: nsd_time_elapsed_seconds
time.elapsed=3600.789012

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Memory and Size Statistics

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size.db.disk

Size of nsd.db on disk, in bytes.Type: Gauge
Prometheus: nsd_size_db_on_disk_bytes
size.db.disk=104857600

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size.db.mem

Size of the DNS database in memory, in bytes.Type: Gauge
Prometheus: nsd_size_db_in_mem_bytes
size.db.mem=134217728

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size.xfrd.mem

Size of memory for zone transfers and notifies in xfrd process, excludes TSIG data, in bytes.Type: Gauge
Prometheus: nsd_size_xfrd_in_mem_bytes
size.xfrd.mem=2097152

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size.config.disk

Size of zonelist file on disk, excludes the nsd.conf size, in bytes.Type: Gauge
Prometheus: nsd_size_config_on_disk_bytes
size.config.disk=65536

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size.config.mem

Size of config data in memory, kept twice in server and xfrd process, in bytes.Type: Gauge
Prometheus: nsd_size_config_in_mem_bytes
size.config.mem=131072

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Zone Statistics

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zone.primary

Number of primary zones served. These are zones with no ‘request-xfr:’ entries. Also output as ‘zone.master’ for backwards compatibility.Type: Gauge
Prometheus: nsd_zones_primary

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zone.secondary

Number of secondary zones served. These are zones with ‘request-xfr’ entries. Also output as ‘zone.slave’ for backwards compatibility.Type: Gauge
Prometheus: nsd_zones_secondary
zone.primary=50
zone.secondary=25

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Per-Zone Statistics

When compiled with --enable-zone-stats, NSD provides per-zone statistics. These follow the same format as global statistics but are prefixed with the zone name.
For each zone, the following statistics are available:
  • zonestats.<zone>.queries - Total queries for this zone
  • zonestats.<zone>.type.X - Queries by type
  • zonestats.<zone>.opcode.X - Queries by opcode
  • zonestats.<zone>.class.X - Queries by class
  • zonestats.<zone>.rcode.X - Answers by rcode
  • zonestats.<zone>.edns - EDNS queries
  • zonestats.<zone>.ednserr - EDNS errors
  • zonestats.<zone>.udp - UDP queries (IPv4)
  • zonestats.<zone>.udp6 - UDP queries (IPv6)
  • zonestats.<zone>.tcp - TCP connections (IPv4)
  • zonestats.<zone>.tcp6 - TCP connections (IPv6)
  • zonestats.<zone>.tls - TLS connections (IPv4)
  • zonestats.<zone>.tls6 - TLS connections (IPv6)
zonestats.example.com.queries=45678
zonestats.example.com.type.A=30000
zonestats.example.com.type.AAAA=15000
Prometheus format:
nsd_zonestats_example_com_queries_total 45678
nsd_zonestats_example_com_queries_by_type_total{type="A"} 30000
nsd_zonestats_example_com_queries_by_type_total{type="AAAA"} 15000

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Prometheus Metrics

When compiled with libevent 2.0 or later, NSD can expose statistics via a Prometheus-compatible HTTP endpoint.
nsd.conf
server:
    # Enable metrics endpoint (default: no)
    metrics-enable: yes
    
    # Metrics endpoint port (default: 9100)
    metrics-port: 9100
    
    # Metrics endpoint path (default: /metrics)
    metrics-path: "/metrics"
    
    # Metrics interface (default: 127.0.0.1 and ::1)
    metrics-interface: 127.0.0.1
    metrics-interface: ::1
Access metrics:
curl http://localhost:9100/metrics
Prometheus metrics use the following naming convention:
  • Prefix: nsd_
  • Metric name: descriptive name with underscores
  • Suffix: _total for counters, _bytes for sizes, _seconds for times
  • Labels: Used for dimensions (e.g., {type="A"}, {server="0"})
Examples:
# HELP nsd_queries_by_type_total Total number of queries received by type.
# TYPE nsd_queries_by_type_total counter
nsd_queries_by_type_total{type="A"} 850000
nsd_queries_by_type_total{type="AAAA"} 250000

# HELP nsd_time_up_seconds_total Uptime since server boot in seconds.
# TYPE nsd_time_up_seconds_total counter
nsd_time_up_seconds_total 86400.123456

# HELP nsd_size_db_in_mem_bytes Size of DNS database in memory.
# TYPE nsd_size_db_in_mem_bytes gauge
nsd_size_db_in_mem_bytes 134217728

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Using Statistics for Monitoring

# Get current query rate
nsd-control stats_noreset | grep num.queries

# Monitor queries per server process
nsd-control stats_noreset | grep server.*queries
Prometheus query for QPS:
rate(nsd_queries_total[5m])

# Check error counters
nsd-control stats_noreset | grep -E "num\.(dropped|rxerr|txerr|ednserr)"
Prometheus query for error rate:
rate(nsd_queries_dropped_total[5m]) +
rate(nsd_queries_rx_failed_total[5m]) +
rate(nsd_answers_tx_failed_total[5m])

# Check memory statistics
nsd-control stats_noreset | grep size
Prometheus query:
nsd_size_db_in_mem_bytes + nsd_size_config_in_mem_bytes + nsd_size_xfrd_in_mem_bytes

# Check zone transfer activity
nsd-control stats_noreset | grep -E "num\.(raxfr|rixfr)"

# Check zone status
nsd-control zonestatus

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Resetting Statistics

By default, nsd-control stats resets all counters to zero after displaying them. This allows you to measure rates over specific time periods. 
# Reset counters after display
nsd-control stats

# Don't reset counters
nsd-control stats_noreset
Time-based counters (time.boot, time.elapsed) and gauge metrics (sizes, zone counts) are not affected by resets.

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Compilation Requirements

Statistics must be enabled at compile time:
# Enable basic statistics
./configure --enable-bind8-stats

# Enable per-zone statistics (includes bind8-stats)
./configure --enable-zone-stats

# Enable Prometheus metrics (requires libevent 2.0+)
./configure --with-libevent
Without these flags, nsd-control stats will return an error.

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See Also

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