Geo DNS and CDN services

What problem are we solving?

For users in mainland China, overseas websites often fail to open reliably even when the server is online. The most common reason is not the web server itself — it is DNS resolution and international routing.

When DNS resolution is slow, the experience from China can look like:

• “Website not found” or “page cannot be displayed”
• The page loads only after 2–3 attempts
• Parts of the page never load (fonts, scripts, analytics tags)

Geo DNS: what it is

Geo DNS means returning different DNS responses based on the user's location. The usual goal is to route users to the nearest server (or nearest region) to reduce latency and improve reliability.

Typical Geo DNS behaviours:

• China users → China/Asia endpoint
• Europe users → EU endpoint
• US users → US endpoint

Why Geo DNS can fail for China

Geo DNS relies on fast, predictable DNS resolution and accurate geo-location from the resolver path. In China, two constraints matter:

• DNS latency: DNS lookups from China to overseas name servers can be hundreds of milliseconds. In fast Chinese networks, slow DNS is often treated as a failure.
• Resolver behaviour: the “location” used by Geo DNS may be the location of the DNS resolver, not the end user, which can reduce accuracy.

CDN: what it is

A Content Delivery Network (CDN) caches and serves web assets (images, CSS, JavaScript, downloads, sometimes full pages) from edge locations close to users.

A CDN typically helps with:

• Faster page loads (especially for images and scripts)
• Lower load on your origin server
• Improved resilience during traffic spikes

CDN reality for China

CDNs can be helpful for China, but only when you account for:

• Compliance: using edge nodes inside mainland China often requires local licensing (ICP-related requirements) and a China-based provider relationship.
• International routing: even when a CDN brand has “China” options, international routing into China can still be inconsistent for certain networks and regions.
• Third‑party dependencies: if your page depends on blocked or heavily throttled services, the CDN will not fix the underlying dependency.

A practical architecture that works

For most overseas businesses, a China-friendly approach looks like this:

1. Buy/manage the China-facing domain via a China-capable supplier so you can use a DNS service that resolves quickly inside China.
2. Use a clear routing plan: China users to an Asia endpoint (Hong Kong / Singapore / Japan / Taiwan, depending on your case), non‑China users to your normal regions.
3. Use a CDN where it makes sense for static assets, but do not assume “global CDN” equals “works in China”.
4. Remove fragile dependencies (e.g., Google-hosted fonts/scripts) by self-hosting or using China-accessible alternatives.

When you should NOT use Geo DNS

• If you cannot make DNS fast inside China.
• If you only have one viable origin and cannot maintain multiple endpoints.
• If your application must maintain strict session affinity, but your routing strategy cannot guarantee it.

Testing: what to measure

Testing from China should include the full journey:

• DNS resolution time (first and repeat)
• TCP/TLS connection time
• Time to first byte (TTFB)
• Third-party resource timing (fonts, scripts, trackers)
• Full visual load time