Public IP tool caching issue?

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Diego Hernandez Author
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2 days ago Asked
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2 Replies
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hey everyone, i'm running a simple "What is my IP Address" web tool and i've noticed some users are reporting issues where their public ip address isn't updating immediately after a change, or they're seeing an old IP for a while. we have a basic tool that just fetches the user's public IP, nothing fancy. the problem is, users with dynamic IPs, or those switching networks, sometimes see their old IP for an extended period, which is really confusing for them. it honestly feels like some super aggressive caching is happening somewhere along the line. i've already tried setting cache-control headers on the server to no-cache, no-store, must-revalidate, but i'm still getting these reports. what are the best practices or common pitfalls for ensuring a "what is my public IP" tool always displays the current IP address, with minimal caching? are there specific CDN or browser caching configurations I should be aware of, or maybe a different fetching method entirely? the goal here is to provide a reliable, real-time public ip address display for users. waiting for an expert reply.
caching ip address web tool public ip

2 Answers

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Valentina Sanchez
Answered 1 day ago
First, a quick note on capitalization: "I'm" always appreciates its uppercase 'I'. Now, regarding your "What is my IP Address" tool, the persistent display of old IP addresses, even with aggressive `Cache-Control` headers, indicates caching layers beyond just your origin server's direct response. This is a common challenge when dealing with network intermediaries. Here are the best practices to ensure reliable, real-time public IP address display:
  • Dedicated, Non-Cacheable Endpoint: While your Cache-Control: no-cache, no-store, must-revalidate headers are correct for preventing caching at the browser and most proxy levels, ensure your server-side endpoint fetching the IP address is inherently dynamic. It should not rely on any internal application-level caching (e.g., Redis, Memcached) or framework-specific caching mechanisms that might serve stale data before your HTTP headers are even processed. Each request to this endpoint should trigger a fresh lookup.
  • Client-Side IP Detection: The most robust method for determining the user's *current* public IP is to perform the lookup directly from the user's browser via JavaScript. Your frontend code should make an asynchronous request (e.g., using fetch or XMLHttpRequest) to your dedicated backend endpoint. To further bypass potential caching, consider appending a unique, non-functional query parameter like a timestamp (/api/get-ip?_t=1678888888) to the request URL. This makes each request URL unique, often forcing intermediaries to treat it as a new request.
  • CDN and Reverse Proxy Configuration: If your web tool is behind a Content Delivery Network (CDN) or a reverse proxy (like Nginx, Cloudflare, Akamai), these services have their own caching layers that can override or ignore origin server headers based on their internal rules. You must explicitly configure these services to *bypass caching* for your specific IP lookup endpoint. Look for settings related to "cache bypass," "page rules," or "edge caching" and ensure requests to your IP endpoint are never cached at the edge. Also, verify that these services are correctly passing the user's original IP address via headers like X-Forwarded-For or CF-Connecting-IP to your backend.
  • Minimal DNS Caching Impact: While less likely to be the primary cause for *user's* IP not updating (as opposed to your server's IP), ensure your domain's DNS records have a relatively low Time-To-Live (TTL) if you anticipate your server's IP changing. However, for client-side IP detection, this is usually not the culprit.
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Diego Hernandez
Answered 1 day ago

Oh nice! Your reply was the best thing I read today.

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