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IP & Network Tools

Look up DNS, MX, nameserver and TXT records, calculate CIDR subnets and convert IP addresses between dotted, decimal, hex, octal and binary forms.

Binary to IP Converter Convert binary IPv4 addresses back to standard dotted-decimal notation. CIDR / Subnet Calculator Calculate network, broadcast, netmask, wildcard, host range and host count for any IPv4 or IPv6 CIDR block. Decimal to IP Converter Convert decimal IPv4 addresses back to standard dotted-decimal notation. DNS Lookup Look up A, AAAA, CNAME, MX, NS, TXT and SOA records for any domain. Hex to IP Converter Convert hexadecimal IPv4 addresses back to standard dotted-decimal notation. Hostname to IP Resolve a hostname to its IPv4 and IPv6 addresses. HTTP Request Headers Viewer See the HTTP request headers your browser sends: User-Agent, Accept, Sec-Fetch and client hints, plus headers added by a CDN or proxy. Cookie values hidden. IP Address Lookup Look up the approximate country, region, city, time zone and network (ASN) of any public IP address, from a local database. IP to Binary Converter Convert an IPv4 address from dotted-decimal notation to binary, shown alongside its other notations. IP to Decimal Converter Convert an IPv4 address from dotted-decimal notation to decimal, shown alongside its other notations. IP to Hex Converter Convert an IPv4 address from dotted-decimal notation to hexadecimal, shown alongside its other notations. IP to Hostname Reverse-DNS lookup: find the hostname (PTR record) for an IP address. IP to Octal Converter Convert an IPv4 address from dotted-decimal notation to octal, shown alongside its other notations. IPv6 to Binary Converter Convert IPv6 addresses to 128-bit binary and show the expanded, compressed and decimal forms. MX Lookup Find the mail exchange (MX) servers and priorities for a domain or email address. Nameserver Lookup Find the authoritative nameservers (NS records) of any domain. Octal to IP Converter Convert octal IPv4 addresses back to standard dotted-decimal notation. Random IP Address Generator Generate random IPv4 or IPv6 addresses — public, private (RFC 1918) or any unicast — for testing. Random MAC Address Generator Generate random MAC addresses in colon, hyphen, Cisco dot or plain format, unicast and locally administered. TXT Record Lookup Read the TXT records of a domain, including SPF, DKIM and verification strings. Website to IP Address Find the IP address a website points to from its link, with plain-English notes on CDNs, shared hosting and changing results. What Is My IP Address See your public IP address (IPv4 or IPv6) instantly, whether it is public, private or CGNAT, its reverse DNS hostname and your browser details.

IP tools for troubleshooting and planning networks

Whether you are setting up email for a domain, debugging why a site does not resolve, planning subnets or reading firewall logs, you need quick answers about IP addresses and DNS. These IP tools combine live DNS lookups with offline calculators and converters.

DNS lookups

These tools query public DNS from our server, so you see what the rest of the internet sees rather than your local cache:

DNS changes can take time to spread because resolvers cache records for their TTL. If a lookup still shows an old value, wait for the TTL to expire.

Calculators and converters

  • The CIDR calculator turns notation like 192.168.10.0/24 into network address, broadcast address, usable host range and subnet mask.
  • IP to decimal, IP to hex, IP to binary and IP to octal (and back) show an address in the forms used by databases, low-level code and some security filters.
  • IPv6 to binary helps when working with IPv6 prefixes.
  • The random IP address generator and random MAC generator create realistic test data.

Common tasks

  • Email not arriving – check MX records, then the SPF and DMARC TXT records.
  • Website moved to a new host – confirm the A record points to the new IP and the nameservers are the ones you expect.
  • Planning an office or cloud network – split a range into subnets with the CIDR calculator and make sure they do not overlap.
  • Verifying a crawler – a reverse lookup of the IP plus a forward lookup of the returned hostname confirms whether traffic really comes from a search engine.

IPv4 and IPv6

IPv4 addresses are 32 bits, written as four decimal numbers, and the available pool is effectively exhausted, which is why private networks and NAT are everywhere. IPv6 addresses are 128 bits, written as eight groups of hexadecimal digits, and are increasingly common on mobile networks and large providers. Many domains have both A (IPv4) and AAAA (IPv6) records.

Good to know

  • A /24 contains 256 addresses, 254 of them usable for hosts; each step in prefix length halves or doubles the size.
  • Private ranges (10/8, 172.16/12, 192.168/16) are not reachable from the internet.
  • The converters and calculators run in your browser; only the DNS lookups need a server request.

Frequently asked questions

Why does the DNS lookup show a different IP than my computer?
Your computer or network may have cached an older record, or use a different resolver. Records update everywhere once their TTL has expired.
What does /24 mean in an IP address?
It is CIDR notation: the first 24 bits are the network part, leaving 8 bits for hosts. A /24 network has 256 addresses, 254 of them usable.
How do I check which mail server handles a domain?
Run an MX lookup. It lists the mail servers for the domain, and the lowest priority number is tried first.
What is reverse DNS?
Reverse DNS maps an IP address back to a hostname using PTR records. It is used for logging, email reputation and verifying crawlers.