Basics · 9 min read · June 1, 2026 · IPLocatorTools

Understanding IP and Network Data in Plain English

Network data, IP addresses, DNS records, and security reports are full of technical jargon. Here is a plain-English guide to understanding what the numbers and codes actually mean.

When you look up an IP address or run a network diagnostic tool, you get back a page of technical information — ASN numbers, CIDR notation, PTR records, TTL values, HTTPS headers, and more. For most people, this data is opaque. This guide translates the most common network data fields into plain English, so you can actually understand what you are looking at.

Your IP Lookup Results — Explained

When you check your IP address at IPLocatorTools, you see several fields. Here is what each one means:

IP Address

Your IP address is the unique numerical identifier assigned to your internet connection by your ISP. It is how servers know where to send data you request.

IPv4 looks like: 203.0.113.42 — four numbers separated by dots, each from 0 to 255. IPv6 looks like: 2001:db8::8a2e:370:7334 — a longer hexadecimal address that was introduced because the world ran out of IPv4 addresses.

Most home connections have both — your device uses IPv6 when it is available, and falls back to IPv4 when it is not. Full explanation: IPv4 vs IPv6 →

City and Country

The approximate geographic location associated with your IP address. This is not your exact location — it is where your ISP's infrastructure that services your IP range is located. For urban broadband users, this is often accurate to the city level. For rural users, it may show the nearest town your ISP uses as a hub.

Why it might be wrong: Your IP is registered to your ISP's regional office, not your home. If you are in a suburb, the lookup might show the nearest major city. Mobile connections often show the city where your carrier's data gateway is located, not where you physically are.

ISP (Internet Service Provider)

The company that owns the IP address block and provides your internet connection. This field shows whether you are on home broadband, mobile data, a corporate network, a VPN, or a cloud provider.

Common examples:

• Comcast Cable Communications — US home broadband
• Vodafone UK — UK mobile or broadband
• Amazon Technologies — AWS cloud server
• Mullvad VPN — Mullvad VPN server (the VPN provider name shows here, not your real ISP)

ASN (Autonomous System Number)

An Autonomous System is a large network or group of networks managed by a single organisation and following a common routing policy. The ASN identifies which network your IP belongs to.

Format: AS15169 (Google LLC)

Every ISP, major company, university, and cloud provider has one or more ASNs. Your home ISP has an ASN for the network block containing your IP. The ASN is used in BGP routing (the protocol that determines how traffic is routed across the internet between different networks).

For most users, the ASN is background information. For network engineers and security researchers, it is useful for understanding IP ownership and routing.

Hostname / PTR Record

The hostname (also called a PTR record or reverse DNS) is the domain name associated with an IP address. Not all IPs have hostnames. When they do, the format often reveals the ISP and sometimes the type of connection.

Examples:

• c-203-0-113-42.hsd1.ca.comcast.net — Comcast residential connection in California
• static.42.113.0.203.clients.your-server.de — Static server IP at Hetzner
• 116.mail.google.com — Google mail server

ISPs often set PTR records automatically for their IP ranges. Mail servers use PTR records for verification — receiving mail servers check that the sending IP's PTR record points back to a hostname consistent with the sending domain.

Coordinates (Latitude and Longitude)

The geographic coordinates associated with the IP's registered location. These feed the map display. They are approximate — typically the coordinates of the ISP's office, data centre, or network hub in that region, not your home address.

Important: These coordinates cannot locate your physical home. They represent the network infrastructure location, not your residence.

DNS Lookup Results — Explained

When you use the DNS Lookup tool, you get back records with several fields:

Record Type

The type of DNS record (A, AAAA, MX, NS, TXT, CNAME, SOA, PTR). Each serves a different purpose:

• A — Maps domain to IPv4 address (google.com → 142.250.80.46)
• AAAA — Maps domain to IPv6 address
• MX — Mail exchange servers (where email for this domain is delivered)
• NS — Nameservers (which servers are authoritative for this domain's DNS)
• TXT — Text data (used for SPF, DKIM, domain verification codes)
• CNAME — Alias (points one domain name to another domain name)
• SOA — Start of Authority (administrative information about the DNS zone)
• PTR — Reverse DNS (maps IP address to hostname)

TTL (Time To Live)

A number in seconds telling DNS resolvers how long to cache this record before checking for updates.

• TTL 300 = cache for 5 minutes
• TTL 3600 = cache for 1 hour
• TTL 86400 = cache for 24 hours

Higher TTL values mean faster DNS resolution (the record is cached) but slower propagation when you change the record. If you are about to migrate a website to a new server, lowering the TTL to 300 beforehand means changes propagate in 5 minutes instead of 24 hours.

MX Priority

MX records have a priority number alongside the mail server hostname. Lower numbers mean higher priority — mail servers try the lowest-priority number first.

Example:

• 10 mail1.example.com
• 20 mail2.example.com

Mail is delivered to mail1.example.com first. If that fails, it tries mail2.example.com. This provides redundancy.

CNAME Chain

A CNAME points one domain to another. That target domain might also be a CNAME. This creates a chain that must be followed to reach the final A record.

Example:

www.example.com → CNAME → example.netlify.app → A → 75.2.60.5

Browsers follow this chain automatically. Overly long CNAME chains add small amounts of DNS lookup latency.

SSL Certificate Results — Explained

When you use the SSL Checker, here is what the results mean:

Certificate Issuer

The Certificate Authority (CA) that verified and signed the certificate. Common issuers:

• Let's Encrypt — Free, automated, 90-day certificates. Used by millions of websites.
• DigiCert — Major commercial CA. Used by large organisations.
• Sectigo — Another major commercial CA.
• Cloudflare — Issues certificates for sites using Cloudflare's CDN.

The issuer affects trust levels. All major CAs are trusted by all major browsers. Let's Encrypt certificates are as trustworthy for HTTPS purposes as paid certificates.

Valid From / Valid Until

The dates the certificate is active. An expired certificate causes browsers to show security warnings and block access.

Common issue: Forgetting to renew. Let's Encrypt certificates are valid for 90 days and should be set to auto-renew. Commercial certificates are valid for up to 398 days.

SANs (Subject Alternative Names)

The list of domain names covered by this certificate. A single certificate can cover multiple domains and subdomains.

Example SANs for a Google certificate:

*.google.com
google.com
*.googleapis.com

The * is a wildcard covering all subdomains. If your subdomain is not in the SANs list, the browser will show a certificate mismatch error.

Protocol Version

The version of TLS (Transport Layer Security) the server supports. TLS 1.3 is the current standard. TLS 1.2 is still widely supported and acceptable. TLS 1.0 and 1.1 are deprecated and should not be used.

If an SSL checker shows TLS 1.0 or 1.1, that is a security issue — those versions have known vulnerabilities.

HTTP Headers — Explained

When you use the HTTP Headers Checker, you see the raw HTTP response headers. Key ones:

Content-Type

Tells the browser what type of content the server is sending.

• text/html; charset=utf-8 — An HTML web page
• application/json — JSON data from an API
• image/png — A PNG image

Cache-Control

Tells browsers and CDNs how to cache the response.

• no-store — Never cache this response
• no-cache — Cache it, but always revalidate before using the cached version
• max-age=31536000 — Cache for one year (used for static assets like images and scripts)
• public — Shared caches (CDNs) can store this
• private — Only the user's browser cache should store this (not CDNs)

Strict-Transport-Security (HSTS)

Tells browsers to only connect to this site over HTTPS, never HTTP. The max-age value is how many seconds to enforce this.

Strict-Transport-Security: max-age=31536000; includeSubDomains

This prevents downgrade attacks where an attacker forces your browser to use unencrypted HTTP.

X-Frame-Options

Controls whether this page can be embedded in an iframe on another website.

• DENY — Never allow framing
• SAMEORIGIN — Only allow framing from the same domain

This prevents clickjacking attacks.

Content-Security-Policy (CSP)

A powerful security header that controls which resources the browser is allowed to load for this page. A properly configured CSP prevents cross-site scripting (XSS) attacks.

Example: Content-Security-Policy: default-src 'self'; script-src 'self' 'nonce-abc123'

A missing CSP header is a common finding in security audits.

Blacklist Check Results — Explained

When you use the IP Blacklist Checker:

Listed vs Clean

Each blacklist shows either listed (your IP is in their database as a spam/abuse source) or clean (not listed).

Spamhaus Zones

Spamhaus is the most important blacklist. It has several sub-lists:

• SBL — Spamhaus Block List: IPs directly sending spam
• XBL — Exploits Block List: IPs compromised by malware or running open proxies
• PBL — Policy Block List: Dynamic residential IPs that should not send email directly (they should use their ISP's mail server)

Being on SBL or XBL is serious. Being on PBL is common for home connections and means your IP should send email through your ISP's outgoing mail server rather than directly.

Frequently Asked Questions

What does "NXDOMAIN" mean in DNS results? NXDOMAIN (Non-Existent Domain) means the domain does not exist in DNS — there are no records of any kind for that name. If you are looking up a subdomain and get NXDOMAIN, the subdomain has not been created.

What does a 301 vs 302 HTTP status code mean? Both are redirects. A 301 is permanent — search engines update their index to point to the new URL. A 302 is temporary — search engines keep pointing to the original URL. Using 301 for permanent redirects is important for SEO.

Why do some domains return multiple A records? Multiple A records mean the domain has multiple servers. DNS round-robin distributes connections between them. This is used for load balancing and redundancy.

What is CIDR notation in IP lookups? CIDR (Classless Inter-Domain Routing) notation like /24 describes a range of IP addresses. 203.0.113.0/24 means all 256 addresses from 203.0.113.0 to 203.0.113.255. ISPs register their IP allocations in CIDR blocks. A /24 is 256 IPs; a /16 is 65,536 IPs.

Related Tools

Use IPLocatorTools to look up any IP address. Use the DNS Lookup tool to query DNS records. Use the SSL Checker to verify SSL certificates. Use the HTTP Headers Checker to inspect server headers. Use the IP Blacklist Checker to check IP reputation.