What a website IP address lookup tells you
Browsers never connect to a name. Before a page loads, DNS translates the site's name into one or more numeric addresses, and the browser connects to one of them. This page repeats that first step for any link you paste and lists the website IP address, or addresses, that the name resolves to at the moment of the lookup. Lines labelled IPv4 are classic addresses; lines labelled IPv6 are the newer, longer kind. A site without IPv6 simply shows IPv4 lines only.
The lookup itself is identical to Hostname to IP. Pick that page when you work with bare host names, record types and resolvers; stay here when you start from a web link and want to understand what the answer means for a website you run or visit.
Reading the result
A result for a site behind a content delivery network might look like this (the addresses are from ranges reserved for documentation):
IPv4 198.51.100.20
IPv4 198.51.100.21
IPv6 2001:db8:10::20| What you see | What it usually means |
|---|---|
| A single IPv4 line | One server or one shared-hosting address serves the site. |
| Several IPv4 lines | The name has several A records, so traffic is spread over more than one server or edge location. |
| IPv6 lines as well | The site also has AAAA records and is reachable over IPv6. |
| Could not resolve … | No address is published for that name: a typo, an expired domain, or DNS that has not been set up yet. |
If the name is an alias that points to another name, the result shows the final addresses, not the alias. To see the alias itself and the record lifetimes (TTL), run a DNS lookup.
Why someone else may see a different IP
- Location-aware answers. Large sites and CDNs hand out addresses near the person asking. The lookup here runs on our server, so a visitor on another continent can legitimately receive a different address for the same link.
- Anycast. Some providers announce one address from many data centres. Everyone sees the same number, yet each visitor reaches the nearest location.
- Recent changes. After you edit a DNS record, resolvers keep serving the previous answer until its lifetime runs out. Two people can therefore see old and new addresses side by side for a while.
- Different names.
www, the bare domain and every subdomain have their own records, so check the exact name your visitors type.
Several IPs for one site, one IP for many sites
A popular site often publishes several addresses for redundancy: if one server is unreachable, browsers try another. Having both IPv4 and IPv6 addresses also counts as several. Any of them should deliver the same pages.
The reverse is just as common. Shared hosting plans and CDNs place many unrelated websites behind the same address, and the server decides which site to deliver from the name the browser sends with each request. That is why typing a shared IP into the address bar rarely opens the site you expected, and why an IP address alone does not identify a single website.
What an IP can and cannot reveal
- It can show which network is answering for the site right now: your hosting company, a CDN or a security proxy. A reverse check with IP to Hostname often returns a provider's server name that makes this obvious.
- It can confirm whether a DNS change is visible from outside your own network.
- It cannot show who owns the website. The address belongs to whoever operates the network, not to the site's owner.
- It cannot show where the original server sits when a CDN is in front; you only see the edge.
- It cannot show whether the site works. Only DNS is queried; the page is never requested.
Checks for site owners
- After moving to a new host: compare the result with the address in the new host's control panel. Seeing the old address means the record has not been changed yet or an earlier answer is still cached.
- After switching on a CDN proxy: the lookup should return the CDN's addresses. If your own server's address still appears, the proxy is not active for that name.
- Email is separate: mail delivery follows MX records, not the website's address. Use the MX lookup for that.
What you can paste
Full links work, including a port, path, query or fragment; the host is extracted and lower-cased. An email address is reduced to the domain after the @ sign. A host with a port but no scheme or slash, such as example.com:8080, is rejected, so paste it with https:// in front. Domains with accented or non-Latin characters are converted to their xn-- form automatically where supported; if the lookup rejects such a name, enter its xn-- form, for example xn--bcher-kva.de for bücher.de. IP addresses, localhost and private names ending in .local, .internal or .lan are not accepted. Our server performs the DNS query, so the host name you enter is sent to it; the website itself is not contacted.