How to check the neighbours on your IP with a reverse DNS lookup

If several sites share one IP address, they are neighbours whether you chose them or not. A reverse lookup lets you see who else lives at that address, which matters when a search engine or a spam blocklist judges the whole block by its worst tenant. This guide shows you how to run the checks, how to read the results honestly, and where a plain reverse DNS lookup stops being enough.

Forward DNS, reverse DNS, and reverse IP: three different things

These terms get muddled constantly, and the confusion leads people to trust the wrong result. Keeping them apart is the whole game.

• Forward DNS answers "what IP does this hostname point to?" You give it example.com and it returns an address.
• Reverse DNS (rDNS) answers "what hostname is registered for this IP?" It reads a special PTR record and usually returns a single name, often the server's own hostname such as srv12.somehost.net rather than any customer domain.
• Reverse IP lookup answers "which domains are hosted on this IP?" This is what most people actually mean when they say they want to "see the neighbours." It is not a DNS record at all; it is a service that has crawled the web and built an index of domain-to-IP mappings.

The practical takeaway: a PTR record almost never lists your neighbours. To enumerate the other sites on an address you need a reverse IP tool. Both are worth running, because each tells you something different.

Run a reverse DNS (PTR) lookup

Start here because it is quick and it confirms which server you are dealing with. First find the IP, then query its PTR record.

1. Find the IP from any machine: dig +short example.com on macOS or Linux, or nslookup example.com on Windows.
2. Query the PTR record for that IP. With dig: dig +short -x 203.0.113.45. With host: host 203.0.113.45. On Windows: nslookup 203.0.113.45.

You will usually get back a single server hostname. That is normal. What you are looking for is a clean, coherent name that matches the host you expect. A missing PTR record, or one that resolves to something unrelated, is worth noting because some mail servers reject messages from IPs with no valid reverse record. That is a deliverability concern more than a ranking one.

Run a reverse IP lookup to find the real neighbours

This is the check that answers the question in the title in the way most people mean it. Reverse IP services maintain their own crawled index, so no two are identical and none is complete. Use more than one and treat the combined picture as a sample, not a census.

• Enter your IP into two or three separate reverse IP tools and compare the domain lists they return.
• Scan the results for obvious bad neighbours: gambling, adult, counterfeit goods, payday loans, pills, and any domain in a language or niche that has nothing to do with the legitimate tenants.
• Cross-check anything suspicious against a blocklist checker. If the IP appears on well-known spam or malware lists, that reputation is shared by every site on it.

Remember the limits. These indexes lag reality by weeks or months, they miss sites that block crawlers, and on a large shared host the tool may only surface a fraction of the addresses. A short, clean list is reassuring but not proof of a quiet block.

What the results actually mean for SEO

Be careful with the conclusions you draw. Google has repeatedly framed spam as a domain-level and content-level problem, and the public guidance in the Search spam policies does not describe demoting a site simply for sharing an IP with a bad actor. A dedicated IP is not a ranking boost, and anyone selling it as one is overstating the case.

The real value is defensive and operational:

• Reputation isolation. Spam blocklists, some security vendors, and mail providers do act at the IP or block level. If your address lands on a list because of a neighbour, your email and sometimes your crawl budget can suffer even when your own site is clean.
• Footprint control for networks. If you run multiple related sites, a reverse IP lookup on your own addresses shows what a competitor or a manual reviewer would see. A cluster of your sites sharing one IP is a pattern; spreading them across genuinely diverse IPs, ideally on separate Class C ranges, breaks that pattern. This is the specific problem that Class C IP hosting is built to solve.

What to do if you find bad neighbours

1. Confirm the blast radius. Check whether the shared IP is on any blocklist. If it is clean, a single unsavoury neighbour is unpleasant but not urgent.
2. Ask your host for a dedicated IP or move the site to one. On a reputable SEO host each site can sit on its own address, which removes you from the shared reputation entirely.
3. Re-check after the move. Run the reverse IP lookup again a few weeks later so the index has time to update and reflect your new, isolated address.

If you operate a network, make this part of a routine. Auditing your own footprint is more useful than chasing rankings; you can read more on that in the IP diversity and search footprint hub, and if you are choosing where to host in the first place our SEO web hosting plans put each site on its own dedicated IP by default.

Quick reference

• Who is my server? Use reverse DNS: dig +short -x YOUR.IP.ADDR
• Who are my neighbours? Use two or three reverse IP tools and compare.
• Should I worry? Only if the IP is on a blocklist, or if your own related sites are clustered on it. A lone bad neighbour with a clean IP reputation is low risk.