DNSCheck

A sysops toolkit for scanning, monitoring, reporting, alerting, tracking top entries, recording usage, checking health, fixing issues, cleaning up, backing up, restoring, logging, benchmarking, and comparing DNS-related operations — all from the command line with full history tracking.

Commands

Command	Description
`dnscheck scan <input>`	Record and review DNS scan entries (run without args to see recent)
`dnscheck monitor <input>`	Record and review monitoring entries
`dnscheck report <input>`	Record and review report entries
`dnscheck alert <input>`	Record and review alert entries
`dnscheck top <input>`	Record and review top-priority entries
`dnscheck usage <input>`	Record and review usage entries
`dnscheck check <input>`	Record and review health check entries
`dnscheck fix <input>`	Record and review fix entries
`dnscheck cleanup <input>`	Record and review cleanup entries
`dnscheck backup <input>`	Record and review backup entries
`dnscheck restore <input>`	Record and review restore entries
`dnscheck log <input>`	Record and review log entries
`dnscheck benchmark <input>`	Record and review benchmark entries
`dnscheck compare <input>`	Record and review comparison entries
`dnscheck stats`	Show summary statistics across all log files
`dnscheck export <fmt>`	Export all data in JSON, CSV, or TXT format
`dnscheck search <term>`	Search across all logged entries
`dnscheck recent`	Show the 20 most recent activity entries
`dnscheck status`	Health check — version, data dir, entry count, disk usage
`dnscheck help`	Show usage info and all available commands
`dnscheck version`	Print version string

Each data command (scan, monitor, report, etc.) works in two modes: - With arguments: Logs the input with a timestamp and saves to the corresponding .log file - Without arguments: Displays the 20 most recent entries from that command's log

Data Storage

All data is stored locally in ~/.local/share/dnscheck/. Each command writes to its own log file (e.g., scan.log, monitor.log, check.log). A unified history.log tracks all activity across commands with timestamps.

Log format: YYYY-MM-DD HH:MM|<input>
History format: MM-DD HH:MM <command>: <input>
No external database or network access required

Requirements

Bash 4+ (uses set -euo pipefail)
Standard POSIX utilities: date, wc, du, head, tail, grep, basename, cat
No root privileges needed
No API keys or external dependencies

When to Use

Logging DNS lookup results — Use dnscheck scan and dnscheck check to record DNS query results for domains, building a searchable history of resolution data over time
Monitoring DNS changes and propagation — Use dnscheck monitor to log periodic DNS state checks across providers, then dnscheck search to find when a record changed
Recording DNS incidents and alerts — Use dnscheck alert and dnscheck report to document DNS outages, misconfigurations, or propagation delays with timestamps
Tracking DNS configuration fixes — Use dnscheck fix and dnscheck cleanup to maintain an audit trail of record changes, stale entry removals, and zone file updates
Benchmarking DNS resolver performance — Use dnscheck benchmark and dnscheck compare to log response times from different DNS resolvers and compare their performance

Examples

Log a DNS scan and review history

# Record a DNS scan result
dnscheck scan "example.com A record: 93.184.216.34 (TTL 3600)"

# View recent scan entries
dnscheck scan

Monitor and alert workflow

# Log a monitoring observation
dnscheck monitor "api.example.com CNAME still pointing to old ALB — propagation pending"

# Log an alert
dnscheck alert "MX records missing for newdomain.com — email delivery failing"

# Generate a report entry
dnscheck report "Weekly DNS audit: 2 stale CNAMEs, 1 missing SPF record"

# Search across all entries
dnscheck search "example.com"

Fix and cleanup tracking

# Log a fix
dnscheck fix "Updated SPF record for company.com to include new mail server IP"

# Log a cleanup
dnscheck cleanup "Removed 5 stale A records from legacy.example.com zone"

# View recent activity
dnscheck recent

Export and statistics

# Summary stats across all log files
dnscheck stats

# Export everything as JSON
dnscheck export json

# Export as CSV for spreadsheet analysis
dnscheck export csv

# Health check
dnscheck status

Benchmark and compare DNS resolvers

# Log a benchmark
dnscheck benchmark "Google DNS (8.8.8.8): avg 12ms for example.com A lookup"

# Log a comparison
dnscheck compare "Cloudflare 1.1.1.1 (8ms) vs Google 8.8.8.8 (12ms) for example.com"

# Backup DNS zone data
dnscheck backup "Exported example.com zone file to /backups/dns/2025-03-18.zone"

# Log a restore
dnscheck restore "Restored example.com zone from backup after accidental deletion"

How It Works

DNSCheck uses a simple case-dispatch architecture in a single Bash script. Each command maps to a log file under ~/.local/share/dnscheck/. When called with arguments, the input is appended with a timestamp. When called without arguments, the last 20 lines of that log are displayed. The stats command aggregates entry counts across all logs, export serializes everything into JSON, CSV, or plain text, and search greps across all log files for a given term.

Support

Website: bytesagain.com
Feedback: bytesagain.com/feedback
Email: [email protected]