Understanding ASN (Autonomous System Number) in Proxy Selection

An ASN (Autonomous System Number) is a unique identifier assigned to a network that operates its own routing policy on the internet. For proxy users, the ASN behind a proxy IP is one of the most important factors in determining whether that proxy will work for a given task. Websites use ASN data to classify traffic as residential, datacenter, or mobile — and they apply different trust levels and blocking rules accordingly.

Choosing proxies with the right ASN is the difference between requests that sail through anti-bot defenses and requests that get blocked before they even reach the target server.

Quick ASN Refresher

Every network on the internet that manages its own IP addresses and routing receives an ASN from a Regional Internet Registry (RIR). Large organizations may have multiple ASNs, while smaller networks share infrastructure under a parent ASN.

ASN Categories

Category	Description	Examples
Residential ISP	Home internet providers	Comcast (AS7922), AT&T (AS7018), BT (AS2856)
Mobile Carrier	Cellular network operators	T-Mobile (AS21928), Vodafone (AS3209)
Cloud/Datacenter	Cloud computing platforms	AWS (AS16509), Google Cloud (AS15169)
Hosting Provider	Server hosting companies	OVH (AS16276), Hetzner (AS24940)
Enterprise	Large corporations	Apple (AS714), Microsoft (AS8075)
CDN	Content delivery networks	Cloudflare (AS13335), Akamai (AS20940)

Why ASN Matters in Proxy Selection

ASN-Based Trust Scoring

Websites and anti-bot services maintain databases that classify ASNs by type. This classification determines the baseline trust level applied to incoming requests:

Request arrives from IP 45.67.89.10
    ↓
Anti-bot system looks up ASN → AS16509 (Amazon AWS)
    ↓
Classification: Datacenter/Cloud
    ↓
Trust level: LOW → Apply strict bot detection rules
    ↓
Result: CAPTCHA, rate limit, or block

Compare with:

Request arrives from IP 73.45.123.67
    ↓
Anti-bot system looks up ASN → AS7922 (Comcast)
    ↓
Classification: Residential ISP
    ↓
Trust level: HIGH → Apply standard rules
    ↓
Result: Normal access

Detection Rates by ASN Type

Based on real-world scraping experience, detection and block rates vary dramatically by ASN type:

ASN Type	Typical Block Rate	CAPTCHA Rate	Best Use Cases
Mobile Carrier	1-5%	2-8%	Social media, high-security targets
Residential ISP	3-10%	5-15%	E-commerce, search engines, general scraping
Business ISP	5-15%	10-20%	B2B platforms, professional sites
ISP-assigned (datacenter-hosted)	10-25%	15-30%	Medium-sensitivity targets
Cloud Provider	30-60%	40-70%	Low-sensitivity targets, APIs
Hosting/VPS	40-70%	50-80%	Non-protected sites only

ASN-Aware Proxy Selection Strategy

Matching ASN to Target

The key principle: your proxy’s ASN should match the type of user the target website expects.

Target Website	Expected User ASN	Recommended Proxy ASN
Amazon, Walmart	Residential ISP	Comcast, AT&T, Spectrum
Instagram, TikTok	Mobile carrier	T-Mobile, Verizon Wireless
LinkedIn	Business ISP or residential	Commercial ISP ASNs
Google Search	Any (but residential preferred)	Residential ISPs
Small business site	Any	Datacenter is fine
Government data portal	Residential/business	Local ISP ASNs

Geographic ASN Matching

Beyond ASN type, geographic consistency between the ASN and the target matters:

Scraping Amazon.com with a Japanese ISP ASN may trigger additional verification
Accessing UK-specific content with a US residential ASN may return wrong results
Target websites expect ASN geography to match the requested content region

# Example: Selecting proxies with ASN targeting
import requests

# Provider that supports ASN targeting via username parameters
proxy_configs = {
    "us_residential": "http://user-country-us-asn-7922:pass@gate.provider.com:7777",
    "uk_residential": "http://user-country-gb-asn-2856:pass@gate.provider.com:7777",
    "us_mobile": "http://user-country-us-asn-21928:pass@gate.provider.com:7777",
}

# Select based on target
target = "https://www.amazon.com/product-page"
proxy = proxy_configs["us_residential"]

response = requests.get(
    target,
    proxies={"http": proxy, "https": proxy}
)

ASN Diversity Strategy

Why You Need Multiple ASNs

Relying on a single ASN for all your scraping traffic creates concentration risk:

Pattern detection: Hundreds of requests from the same ASN with similar behavior signals automation
ASN-level bans: Some websites blacklist entire ASNs when abuse is detected
Rate limiting per ASN: Sophisticated sites apply rate limits per ASN, not just per IP
Fingerprint correlation: Same ASN + similar browser fingerprint = easy to correlate requests

Recommended ASN Distribution

For a robust scraping operation, distribute traffic across multiple ASN types and specific ASNs:

Traffic Share	ASN Type	Purpose
40-50%	Residential ISP (mixed)	Primary scraping traffic
20-30%	Mobile carrier	High-security targets, social media
10-20%	Business ISP	B2B platforms, professional sites
10%	Secondary residential ISPs	Diversity buffer

Monitoring ASN Performance

Track how different ASNs perform against your target websites:

from collections import defaultdict

class ASNPerformanceTracker:
    def __init__(self):
        self.stats = defaultdict(lambda: {"success": 0, "blocked": 0, "captcha": 0})

    def record(self, asn, result):
        """Record the outcome of a request through a specific ASN"""
        self.stats[asn][result] += 1

    def get_success_rate(self, asn):
        """Calculate success rate for an ASN"""
        s = self.stats[asn]
        total = s["success"] + s["blocked"] + s["captcha"]
        if total == 0:
            return 0
        return s["success"] / total * 100

    def report(self):
        """Print performance report for all ASNs"""
        print(f"{'ASN':<15} {'Success%':<10} {'Total':<8} {'Blocked':<10} {'Captcha':<10}")
        print("-" * 55)
        for asn, s in sorted(self.stats.items()):
            total = s["success"] + s["blocked"] + s["captcha"]
            rate = self.get_success_rate(asn)
            print(f"{asn:<15} {rate:<10.1f} {total:<8} {s['blocked']:<10} {s['captcha']:<10}")

# Usage
tracker = ASNPerformanceTracker()
tracker.record("AS7922", "success")
tracker.record("AS7922", "success")
tracker.record("AS16509", "blocked")
tracker.report()

How to Look Up and Verify ASN

Checking a Proxy’s ASN

Before relying on a proxy, verify its ASN:

import requests

def check_proxy_asn(proxy_url):
    """Check the ASN of a proxy IP"""
    proxies = {"http": proxy_url, "https": proxy_url}

    # Get public IP through the proxy
    ip_response = requests.get("https://httpbin.org/ip", proxies=proxies, timeout=10)
    public_ip = ip_response.json()["origin"]

    # Look up ASN information
    asn_info = requests.get(f"https://ipinfo.io/{public_ip}/json").json()

    print(f"Proxy IP: {public_ip}")
    print(f"ASN/Org: {asn_info.get('org', 'Unknown')}")
    print(f"Country: {asn_info.get('country', 'Unknown')}")
    print(f"City: {asn_info.get('city', 'Unknown')}")

    return asn_info

Red Flags in ASN Data

Watch for these issues when checking your proxy’s ASN:

Red Flag	What It Means
Cloud provider ASN when expecting residential	Provider is misrepresenting proxy type
ASN country mismatch with targeted geo	IP geolocation does not match ASN registration
Known proxy/VPN ASN	IP is flagged in anti-bot databases
Very small/unknown ASN	May be a proxy-specific network, easily blocked
ASN associated with abuse	Previously used for spam or attacks

ASN Blocklists and Reputation

Commonly Blocked ASNs

Certain ASNs are frequently blocked by anti-bot systems:

Major cloud providers: AS16509 (AWS), AS15169 (Google), AS14061 (DigitalOcean)
Budget hosting: AS16276 (OVH), AS24940 (Hetzner), AS63949 (Linode)
Known proxy networks: ASNs specifically registered by proxy providers
Bulletproof hosting: ASNs associated with abuse-tolerant hosting providers

ASN Reputation Recovery

If an ASN gets a poor reputation:

The entire ASN’s traffic faces increased scrutiny on affected websites
Recovery requires sustained clean traffic over weeks or months
Individual IPs within the ASN cannot escape ASN-level reputation
This is why shared datacenter hosting has inherently lower trust

Frequently Asked Questions

Can I choose specific ASNs with my proxy provider?

Many premium proxy providers offer ASN-level targeting. This is more common with residential and ISP proxy services. You typically specify the desired ASN through username parameters or API settings. Not all providers offer this feature — check your provider’s documentation.

Does ASN matter more than IP reputation?

Both matter, but ASN provides the initial classification. An IP from a residential ASN starts with higher trust than one from a datacenter ASN. However, an individual IP with poor reputation will still get blocked regardless of its ASN. Think of ASN as your first impression and IP reputation as your track record.

How many ASNs should I use for a scraping project?

For serious scraping operations, aim for at least 5-10 different ASNs, ideally mixing residential ISPs from multiple providers. For highly protected targets, 20+ ASNs provide better resilience against ASN-level blocking or rate limiting.

Why do mobile carrier ASNs have the highest trust?

Mobile carrier IPs are naturally shared among thousands of users via CGNAT. Websites know that blocking a mobile carrier IP would affect many legitimate users, so they apply more lenient rules. Additionally, mobile traffic represents a huge share of legitimate web usage, making it the baseline “trusted” traffic type.

Can I get my own ASN for proxy purposes?

Technically yes, but it is impractical for most proxy users. Getting an ASN requires justifying a multi-homed network setup and costs approximately $500-1,000 annually. A new, unknown ASN would also start with neutral reputation and could be quickly identified as proxy-related by anti-bot services.