IP tools: what they're really for
Understanding an IP address helps solve most network incidents. An IP tells you who owns it, where it seems to come from and sometimes what hostname is associated with it. With these three angles, you identify a blockage, abuse or simple misconfiguration faster. You also know what to give to technical support so they can act without wasting time.
Common use cases:
- Diagnose a block → WHOIS IP identifies the owner and abuse contact
- Verify email deliverability → PTR confirms the server's reverse resolution
- Whitelist an address → My IP shows your exact public address
- Plan a network → The netmask calculator sizes your IPv4 subnets
- Analyze an IPv6 subnet → The IPv6 calculator details prefix, range and reverse DNS
How to use IP tools
Step 1: Choose the tool
| Need | Tool to use |
|---|---|
| Reverse resolve an IP | PTR (reverse) |
| Identify IP owner | WHOIS IP |
| See my public IP | My IP address |
| Calculate subnet mask | IPv4 netmask |
| Analyze an IPv6 subnet | IPv6 subnet calculator |
Step 2: Enter the address
Input the IPv4 or IPv6 address to analyze. Accepted formats:
- IPv4:
192.168.1.1 - IPv6:
2001:db8::1 - CIDR:
192.168.1.0/24
Step 3: Analyze the results
Each tool displays specific information:
- PTR: Associated hostname, TTL, consistency validation
- WHOIS: Organization, contacts, CIDR block, country
- My IP: IPv4, IPv6, geolocation, ISP
- Netmask: Network, broadcast, wildcard, host count
- IPv6: CIDR, address range, compressed/expanded forms, reverse DNS
Tool details
PTR (reverse resolution)
Identifies the hostname associated with an IP address:
| Field | Description |
|---|---|
| Hostname | Name returned by the PTR record |
| TTL | Cache duration of the record |
| Consistency | Verifies if hostname resolves back to the original IP |
Use case: Validate email server configuration or identify suspicious hosts in logs.
WHOIS IP
Reveals the owner and contacts for an IP range:
| Field | Description |
|---|---|
| Organization | Name of responsible entity |
| CIDR block | Assigned address range |
| Abuse contact | Email for reporting incidents |
| Country | Declared location of the block |
Use case: Open an abuse ticket, verify cloud provider ownership, or document an attack.
My IP address
Shows your public address as seen from the Internet:
| Field | Description |
|---|---|
| IPv4 | Public IPv4 address |
| IPv6 | Public IPv6 address (if available) |
| Geolocation | Country, region, approximate city |
| ISP | Detected internet service provider |
Use case: Whitelist your IP, verify VPN effect, or diagnose NAT issues.
IPv4 netmask calculator
Calculates subnet parameters:
| Field | Description |
|---|---|
| Network address | First address of the subnet |
| Broadcast | Last address (broadcast) |
| Mask | Mask in decimal notation |
| Wildcard | Inverse mask for ACLs |
| Usable hosts | Number of assignable addresses |
Use case: Plan addressing, configure a firewall, or document a migration.
IPv6 subnet calculator
Calculates IPv6 subnet parameters:
| Field | Description |
|---|---|
| CIDR | Full block notation (e.g. 2001:db8::/32) |
| Address range | First and last address of the subnet |
| Forms | Compressed, expanded, full and reverse DNS (ip6.arpa.) |
| Address type | Annotation (Global Unicast, Link-Local, ULA, etc.) |
| Prefix size | Prefix length and total address count |
Use case: Plan IPv6 addressing, generate ip6.arpa PTR entries, or verify address type.
FAQ - Frequently asked questions
Q: How do I find the owner of an IP address?
A: Use the WHOIS IP tool by entering the address. The tool queries regional registries (RIPE, ARIN, APNIC, etc.) and displays the responsible organization, abuse/admin contacts, and the assigned CIDR block.
Q: What is a PTR record and why is it important?
A: A PTR record maps an IP address to a hostname (reverse resolution). It's crucial for email deliverability: mail servers verify that the PTR matches the sending server's hostname.
Q: How do I calculate a subnet mask?
A: Enter an address with CIDR notation (e.g., 192.168.1.0/24) in the calculator. The tool displays network address, broadcast, decimal mask, wildcard, and usable host count.
Q: Why are my IPv4 and IPv6 addresses different?
A: Your ISP may assign distinct IPv4 and IPv6 addresses. IPv6 is often native while IPv4 may be shared via CGNAT. Both can coexist on the same connection.
Q: Is IP geolocation accurate?
A: Geolocation is approximate. It depends on third-party databases and can be affected by VPNs, proxies, or CDNs. Use it as an indication, not as proof.
Q: How do I verify PTR/A consistency?
A: A correct configuration means: the IP resolves to a hostname via PTR, and that hostname resolves back to the same IP via A or AAAA. Test both directions with our tools.
Q: How do I calculate an IPv6 subnet?
A: Enter an IPv6 address with its CIDR prefix (e.g. 2001:db8::/32) in the IPv6 subnet calculator. The tool displays the address range, compressed and expanded forms, reverse DNS (ip6.arpa.) and address type.
Complementary tools
| Tool | Purpose |
|---|---|
| DNS Lookup | Resolve DNS records for a domain |
| SPF Inspector | Validate SPF configuration (includes authorized IPs) |
| Propagation Test | Check global DNS propagation |
| CSR Parser | Analyze a certificate signing request before submitting it |
Useful resources
- RFC 1035 - DNS PTR records (PTR record specification)
- RIPE NCC - WHOIS Database (European registry)
- ARIN WHOIS (North American registry)
- RFC 4632 - CIDR (subnet notation)