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Ahmed

Custom Domain DNS Cache aur NXDOMAIN

Case 1 — Custom Domain par DNS_PROBE error

Section titled “Case 1 — Custom Domain par DNS_PROBE error”

Status: Resolved
Date: 7 November 2026
Affected host: ahmed.digitalstudio.ltd

Kya hua?

Section titled “Kya hua?”

Astro aur Starlight ki site Cloudflare Worker par deploy ho chuki thi, lekin laptop browser par “This site can’t be reached”, “DNS address could not be found” aur DNS_PROBE_POSSIBLE nazar aa raha tha.

Kya verify kiya gaya?

Section titled “Kya verify kiya gaya?”
  • Cloudflare zone digitalstudio.ltd active thi.
  • Authoritative nameservers curt.ns.cloudflare.com aur melinda.ns.cloudflare.com sahi jawab de rahe thay.
  • Custom Domain ahmed.digitalstudio.ltd Worker ahmed-starlight ke saath enabled tha.
  • HTTPS certificate valid tha. Jahan DNS resolve ho raha tha, homepage HTTP 200 de raha tha.
  • Cloudflare DNS initially A records resolve kar raha tha, jabke Google DNS-over-HTTPS ne ek check par Status: 3 (NXDOMAIN) diya. Baad mein Google aur doosre public resolvers bhi correct A/AAAA records return karne lage.
  • DNS SOA ke negative caching ka interval 1800 seconds (30 minutes) observe hua. Ye exact device-cache duration ka proof nahi.

Root-cause assessment

Section titled “Root-cause assessment”

Strong evidence: Naya DNS name public resolvers par alag alag waqt par available hua; kuch jagah purana negative DNS answer cache tha.

Confirmed nahi: Koi specific router, ISP, browser cache ya Cloudflare Tunnel ka exact component guilty tha — un sab ka direct failing-state log available nahi tha.

Kya actions hue?

Section titled “Kya actions hue?”
  1. Worker aur Custom Domain mapping ko API se verify kiya.
  2. Cloudflare workers.dev fallback address enable kiya, taa-ke alternative working URL rahe.
  3. Authoritative nameserver, Google, Cloudflare aur Quad9 resolvers se A/AAAA responses check kiye.
  4. HTTPS response verify kiya: 200 aur valid TLS.
  5. Jab cache expire/update hua to domain public resolvers par consistently resolve hone laga.

Is issue ke liye Cloudflare Tunnel create ya configure nahi kiya gaya, kyunke website directly Worker par chalti hai.

Future diagnostic commands

Section titled “Future diagnostic commands”
Terminal window
dig @curt.ns.cloudflare.com ahmed.digitalstudio.ltd A
dig @1.1.1.1 ahmed.digitalstudio.ltd A
dig @8.8.8.8 ahmed.digitalstudio.ltd A
dig @8.8.8.8 ahmed.digitalstudio.ltd AAAA
curl -I https://ahmed.digitalstudio.ltd/

Agar authoritative DNS mein record maujood ho aur kisi recursive resolver mein NXDOMAIN ho, to pehle DNS caching/propagation check karein. Working DNS record ko bina wajah delete/recreate na karein.

Final verification

Section titled “Final verification”

Main domain, Getting Started aur Starlight search assets HTTP 200 return kar rahe thay. Backup Worker address bhi HTTP 200 tha.