How to find out who hosts a website
Sometimes you need to know which provider a site sits on: before a migration, when buying someone's project, or when you have to file an abuse complaint. The host is not printed on the page, but it is almost always visible from the IP address, the reverse PTR record, and the network number (ASN). Here is how to walk that chain by hand and where it can mislead you.
Check your site
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Find the site's IP address
Open a terminal and run nslookup your-domain or ping your-domain: the reply shows the IP from the A record. Windows has nslookup; on Linux and macOS dig +short your-domain is handier. This is the IP of the server the site physically lives on, unless a CDN sits in front.
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Check the reverse (PTR) record
PTR, or reverse DNS, often names the host's server directly. Run nslookup IP or dig -x IP: the answer may read like server123.provider-hostname.net. The name in the PTR is usually the fastest way to recognise the hosting.
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Identify the network (ASN) and its owner
Every IP block belongs to an autonomous system (ASN). Its owner is the network operator the host rents bandwidth or racks from. You can find the ASN and organisation name through WHOIS on the IP or Team Cymru data. Sometimes the ASN is the host itself, sometimes it is a larger data centre it sits in.
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Run WHOIS or RDAP on the IP
WHOIS (the modern form is RDAP) on the IP shows which organisation the block is registered to, the country, and the abuse contact. This helps when the PTR is empty or unhelpful. Do not confuse domain WHOIS (the registrar) with IP WHOIS (the network owner): they are different things.
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Check whether a CDN is in front
If the IP belongs to Cloudflare, Fastly, or another CDN, you are seeing a proxy, not the real hosting. The tell is a CDN name in the PTR and ASN. In that case the domain's nameservers and mail MX records point to the true provider, since they usually stay on the host's side.
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Allow for resellers and shared hosting
On cPanel/LiteSpeed shared hosting dozens of sites share one IP, and the PTR shows the data centre's server name, not the brand you bought the hosting under. So the network owner and the brand you paid can differ, and that is normal.
How to verify the result
The fastest way to run the whole chain at once is the free TechGuard hosting checker (Who hosts this site): it shows the detected host, the IP, PTR, ASN, and network operator, plus the DNS and mail provider and whether a CDN is present. If your manual results match it, you did it right.
Tip: The most common mistake is taking a CDN for the hosting. If the ASN says Cloudflare, the real server is hidden behind a proxy, and you should look for the provider through the nameservers and MX records, not the visible IP.