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Use when working with DNS records, propagation debugging, or domain routing
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SOC 職業分類に基づく
Use before any DevOps build, change, or new feature — refine requirements through dialogue before touching infrastructure or code
Use when working with Docker — building images, writing Dockerfiles, debugging container issues
Use to execute a written implementation plan via subagents with review checkpoints
Use when implementation is complete, all tests pass, and you need to decide how to integrate the work - guides completion of development work by presenting structured options for merge, PR, or cleanup
Use when working with Kubernetes or Helm — authoring, reviewing, hardening, or debugging manifests, Deployments, Services, Ingress, RBAC, NetworkPolicy, or cluster operations
Use when receiving code review feedback, before implementing suggestions, especially if feedback seems unclear or technically questionable - requires technical rigor and verification, not performative agreement or blind implementation
| name | dns-and-domains |
| description | Use when working with DNS records, propagation debugging, or domain routing |
# Basic lookup
dig example.com
dig example.com A # A record (IPv4)
dig example.com AAAA # IPv6
dig example.com CNAME # CNAME
dig example.com MX # mail
dig example.com TXT # text records (SPF, DKIM, etc.)
dig example.com NS # nameservers
# Query a specific DNS server
dig @8.8.8.8 example.com
# Check propagation (query authoritative nameserver directly)
dig example.com NS # get nameservers
dig @<nameserver> example.com # query authoritative NS
# Reverse lookup (IP → hostname)
dig -x 1.2.3.4
| Symptom | Cause | Fix |
|---|---|---|
| NXDOMAIN | Record doesn't exist | Create the record |
| Old IP after update | TTL not expired yet | Wait, or lower TTL before changes |
| Works on some networks, not others | Propagation still in progress | Wait up to 48h |
| CNAME conflict | CNAME at root/apex (not allowed) | Use ALIAS/ANAME record instead |
| SSL cert error after DNS change | Old IP cached | Flush local DNS cache |
# Check from multiple locations
dig @8.8.8.8 example.com # Google
dig @1.1.1.1 example.com # Cloudflare
dig @9.9.9.9 example.com # Quad9
# Local DNS cache flush
# macOS
sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
# Linux
sudo systemd-resolve --flush-caches
# Windows
ipconfig /flushdns
| Type | Use |
|---|---|
A | Maps hostname → IPv4 address |
AAAA | Maps hostname → IPv6 address |
CNAME | Alias of another hostname (not at root) |
MX | Mail server for the domain |
TXT | Text data — SPF, DKIM, verification tokens |
NS | Nameservers for the domain |
SOA | Start of authority — zone metadata |
PTR | Reverse DNS (IP → hostname) |