IPinfo intentionally does not include subdomains when identifying domains for Autonomous System Numbers (ASNs). We only use root/apex domains (e.g., airtel.com) rather than subdomains (e.g., sc.airtel.com).
What’s the reasoning behind this decision?
While extracting subdomains is technically straightforward, supporting them introduces significant complexity:
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Ownership ambiguity: It’s difficult to programmatically determine when a subdomain represents a distinct operational entity versus just a technical subdivision of the parent organization.
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Inclusion criteria: There’s no clear, consistent rule for when a subdomain should be treated as the primary identifier for an ASN versus the parent domain.
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Coverage limitations: Subdomain information is inconsistently available across different data sources and WHOIS records.
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Validation challenges: Contextual URL parsing via regex or similar methods cannot reliably distinguish legitimate organizational subdomains from technical or temporary ones.
What about multinational telecoms that use country-specific subdomains?
We recognize that some global telecommunications companies use subdomains to identify national operations (e.g., sc.airtel.com for Airtel Seychelles). However, the broader complexity and edge cases introduced by subdomain support outweigh the benefits for these specific scenarios.
Our current approach prioritizes:
- Consistency: A clear, predictable rule (root domains only)
- Data quality: Minimal ambiguity in domain attribution
- Maintainability: Reduced complexity in data processing pipelines
What domain will IPinfo show for ASNs with country-specific subdomains?
IPinfo will display the root domain from WHOIS records when available. If multiple domains are candidates, our algorithm prioritizes domains that:
- Appear in official WHOIS records
- Match the country context when possible
- Reflect current ownership information