What Is the Timestamp TXT Record in is-a.dev? Purpose and Usage

The _zone-updated TXT record is a Unix timestamp (in milliseconds) automatically injected into every DNS zone generation to provide a public, machine-readable marker of when the is-a.dev zone was last refreshed.

The is-a-dev/register repository automates DNS management for thousands of developer subdomains. Within its DNS configuration pipeline, a special timestamp TXT record serves as a critical metadata signal. This record, named _zone-updated, is generated every time the zone file is rebuilt, offering transparency and operational utility for both maintainers and users.

How the Timestamp TXT Record Works in is-a.dev

The record generation happens in the core DNS configuration script. In dnsconfig.js at lines 146-148, the code appends a TXT record containing the current millisecond timestamp:

// dnsconfig.js – line 146‑148
// Append a TXT record that stores the current timestamp (ms since epoch)
records.push(TXT("_zone-updated", "\"" + Date.now().toString() + "\""));

Date.now() captures the exact moment of zone compilation. Because this script runs whenever pull requests are merged or domains are modified, the timestamp TXT record always reflects the most recent zone build time.

Why is-a.dev Uses a Timestamp TXT Record

The _zone-updated record serves four primary operational functions according to the is-a-dev/register source code:

• Cache busting: Cloudflare and downstream resolvers cache DNS responses. The changing timestamp forces recognition of zone updates, helping external tools detect fresh configurations without waiting for TTL expiration.
• Change detection: Users can query the record to verify that recent pull requests have been deployed. A simple DNS lookup reveals exactly when the zone was last regenerated.
• Audit trail: The public timestamp provides a lightweight, tamper-evident log of service activity. It records configuration updates without exposing internal identifiers or sensitive metadata.
• Automation: CI pipelines and monitoring scripts can poll _zone-updated to trigger downstream actions, such as cache invalidation or deployment notifications, based on the exact zone build time.

Querying and Using the is-a.dev Timestamp Record

You can interact with this record programmatically or via command-line tools.

Command Line Query with dig

Retrieve the current timestamp directly from DNS:

# Using dig (or any DNS lookup tool)

dig TXT _zone-updated.is-a.dev +short

# Example output:

"1710189234567"

Converting the Timestamp

The returned value is a Unix timestamp in milliseconds. Convert it to human-readable format:

# Bash conversion

ts=$(dig TXT _zone-updated.is-a.dev +short | tr -d '"')
date -d @"$((ts/1000))"

# => Fri Mar 10 14:33:54 UTC 2026

Programmatic Access in Node.js

Automate monitoring by reading the record in your applications:

const { execSync } = require('child_process');

function getZoneUpdate() {
  const raw = execSync('dig +short TXT _zone-updated.is-a.dev')
    .toString()
    .trim()
    .replace(/"/g, '');
  const ms = Number(raw);
  return new Date(ms);
}

console.log('Zone last updated at:', getZoneUpdate().toISOString());

Summary

• The timestamp TXT record (_zone-updated) is automatically generated in dnsconfig.js (lines 146-148) using Date.now().
• It provides a public Unix timestamp in milliseconds indicating the exact moment the is-a.dev DNS zone was last rebuilt.
• The record enables cache busting, change detection, and automation for users and maintainers monitoring the service.
• You can query it via standard DNS tools like dig to verify deployment timing or integrate it into monitoring scripts.

Frequently Asked Questions

What is the exact name of the timestamp TXT record in is-a.dev?

The record is named _zone-updated. It is a TXT record placed at the apex of the is-a.dev zone, meaning you query it as _zone-updated.is-a.dev.

How often does the is-a.dev timestamp TXT record update?

The record updates every time the DNS zone is regenerated. This occurs whenever a pull request is merged, a domain is added or removed, or any DNS record changes are processed by the is-a-dev/register repository's automation pipeline.

Can I rely on the _zone-updated record for monitoring deployments?

Yes. Because the value changes only when the zone file is rebuilt, polling _zone-updated via DNS queries provides a reliable signal that new configurations have propagated. You can compare timestamps to detect when your specific subdomain changes have taken effect.

Does the timestamp TXT record affect DNS resolution for my subdomain?

No. The _zone-updated record is purely informational metadata. It does not impact how resolvers handle your A, CNAME, MX, or other functional records. It serves only as a diagnostic and monitoring tool for the zone's generation time.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}