Connect to the same page through two different proxies and one serves the content cleanly while the other shows a CAPTCHA. Both speak the same protocol, both are elite, neither adds extra headers. The difference comes down to who the IP address belongs to . The technical name for this "identity" is the ASN, and it is the single strongest signal in modern bot detection.
In this article we cover what an ASN is, how a reputation score is built, and what should drive your proxy choice.
What Is an ASN?
Autonomous System Number (ASN) is the number that identifies the organization managing a block of IP addresses within the internet's routing architecture. Every internet service provider, every large datacenter and every mobile operator holds one or more ASNs. These records are public — anyone can query them in the databases of the regional internet registries (RIPE, ARIN, APNIC).
A site that sees an IP address can learn all of the following within a millisecond:
- Which ASN the IP belongs to and what type that ASN is (ISP, hosting, mobile, corporate).
- The name and country of the organization that owns the ASN.
- The block the IP sits in and the size of that block.
- When the block was allocated and how many times it has changed hands.
Lists of hosting ASNs are public and well maintained. That is why hiding the fact that a datacenter IP "comes from a datacenter" is not practically possible.
How Is a Reputation Score Built?
The ASN alone is not enough; the reputation score that sites and security providers use combines many signals. Here is what a typical scoring model looks at:
The score looks at the combination, not any single axis. Even a clean datacenter IP stays low on the ASN axis, which is why it isn't enough on its own against tightly protected targets.
| Signal | What it measures | What drives a bad score |
|---|---|---|
| ASN type | Hosting or subscriber network | Belonging to a known cloud provider |
| Blacklist history | Spam, attack and abuse records | The same IP having been reported before |
| Geographic consistency | Whether the IP's country matches the other signals | IP in Germany, language Turkish, time zone US |
| Block density | Number of requests coming from the same block | An entire /24 block sending requests at once |
| Traffic pattern | Resemblance to human behavior | Fixed-interval requests with zero mouse movement |
| Open ports | Whether the IP has an open proxy port | Showing up in public proxy scans |
Why Does the Same IP Work on One Site and Not Another?
Because reputation is not absolute but contextual. Every site sets its own threshold:
News and blog sites
Usually unprotected, or they apply only basic rate limiting. Datacenter IPs work without trouble.
E-commerce and marketplaces
Mid-level protection; datacenter IPs draw CAPTCHAs often. ISP proxy is usually enough.
Search engines
They turn aggressive under heavy querying. The residential pool and a low request rate are needed.
Social media platforms
The strictest group. For account operations, usually only mobile proxy delivers acceptable results.
This tiering is the foundation of the strategy we describe in in our pool article : try the cheap source first, escalate only when you have to.
How Can You Check IP Reputation Yourself?
You won't see a definitive "score" — every provider's model is closed. But you can read the indirect indicators:
The fastest and most realistic test is the target itself. General reputation services point the way, but they don't replicate the target's decision.
You can see which country and provider your exit IP appears to belong to on the My IP Address page, and check the address's liveness and anonymity level with the proxy checker tool .
The Subnet Effect: Your Neighbor Binds You
Reputation is often calculated not per individual IP but at block level . If a few of the 256 addresses in the same /24 block have been abused, the entire block can be treated as suspect. This is the biggest hidden risk of using shared proxies.
In cheap datacenter packages, hundreds of IPs come from the same block. If that block gets blocked, your entire pool goes down at once. That is why "how many different blocks" matters as much as "how many IPs".
Subnet diversity — how to measure it and why it matters — is covered in a separate article in detail.
Can an ASN Be Changed?
No — the ASN is tied to the allocation of the IP block and cannot be changed by the user. "Making a datacenter IP look residential" is technically impossible. The only thing you can do is use an IP that genuinely exits from a different ASN.
That is why the difference between proxy types is not marketing but infrastructure:
| Type | ASN source | Typical trust | Cost |
|---|---|---|---|
| Datacenter | Hosting provider | Low | Lowest |
| ISP | A real ISP, hosted in a datacenter | High | Medium |
| Residential | The ISP of home subscribers | Very high | High (GB-based) |
| Mobile | GSM carrier | Highest | Highest |
Note the interesting position of the ISP proxy: physically it sits in a datacenter, yet its IP block is registered to a real internet service provider. That pairs datacenter speed with residential trust. For the details, see our ISP vs residential comparison .
Protecting Reputation: Managing Behavior
You can burn a good IP through bad usage. To protect your reputation:
Burning an IP's reputation takes minutes; earning it back takes days. That is why respecting rate limits is more economical than growing the pool.
Summary
The ASN is an IP's identity card, and it cannot be changed. Sites build a reputation score by looking first at the ASN type, then at history, block density and behavior patterns. Datacenter IPs are fast and cheap but start out at a disadvantage on the ASN axis; residential and mobile sources remove that disadvantage. The right move is to build a pool tiered to the target's level of protection. To test your addresses, use proxy checker, and for geographic verification, use My IP Address tools.