Location
Richardson, United States
Within about 20 km
Domain
instructorphp.com
Hosted on Linode in Richardson.
Still looking this up. This tab fills in as the answers arrive.
Network Every network on the internet has an autonomous system number (ASN). This is the one that announces this address.
AS63949Akamai
Linode · Richardson
BGP prefixPrefix The block of addresses this IP is announced in to the rest of the internet. RPKI valid means the block's owner signed off on the network announcing it.
RPKI valid66.228.48.0/21
Seen by 2,817 peers
Latency Round trip for an HTTPS request from your browser to the site and back, including the server's reply time.
Live— ms
Measuring from your browser…
At a glance
Route
Finding a probe near you…
Networks crossed
Each network is an autonomous system (AS). Your traffic is handed from one to the next where they connect, following
the routes BGP advertises.
- AS16509Anthropic, PBC
- AS63949Akamai
Tracing from a probe near you with Globalping. Hop locations that its round-trip times rule out are left off the map.
Can be spoofed
There's no SPF or DMARC record, so anyone can send mail that claims to be from instructorphp.com.
- Receives mail
- No mail servers
- SPFLists the servers allowed to send mail for the domain. Receivers check it against the sending server.
- Missing
- DMARCTells receivers what to do with mail that fails SPF and DKIM: nothing (none), spam folder (quarantine) or reject.
- Missing
- MTA-STSRequires other mail servers to use encrypted connections (TLS) when delivering to this domain.
- Not published
- TLS reportsAsks other mail servers to report failed encrypted deliveries (TLS-RPT).
- Not requested
- BIMIA brand logo that some mail apps show next to authenticated mail from the domain.
- Not published
DNS records
TypeNameValueTTL
Ainstructorphp.com66.228.55.19730 sec
NSinstructorphp.comns3.linode.com1 day
NSinstructorphp.comns1.linode.com1 day
NSinstructorphp.comns5.linode.com1 day
NSinstructorphp.comns2.linode.com1 day
NSinstructorphp.comns4.linode.com1 day
CAAinstructorphp.com0 issue "letsencrypt.org"5 min
Exposure
Open ports
2 open- 22SSH
- 80HTTP
- Software
- OpenSSH 8.9p1Ubuntunginx
- Tags
- Cloud
- Seen asHostnames Shodan has seen pointing at, or presented by, this address.
- 66-228-55-197.ip.linodeusercontent.com
From Shodan InternetDB, updated weekly.
HTTPS
Certificate
Valid- Issuer
- Let's Encrypt
- Issuing CA
- YE1
- Covers
- instructorphp.com, www.instructorphp.com
Aug 7, 202624 days leftNov 5, 2026
From Certificate Transparency logs, via Cert Spotter.
Security
B- HSTSStrict-Transport-Security makes browsers refuse plain HTTP to this site. Preloaded sites are HTTPS-only even on a first visit.
- 1 day
- HTTP → HTTPSWhether the plain http:// address redirects visitors to the secure one.
- Redirects
- HTTP/3The newest HTTP, over QUIC. Announced in the alt-svc header or the domain's HTTPS DNS record.
- Not announced
- CAADNS records naming the only certificate authorities allowed to issue certificates for the domain.
- Let's Encrypt
- security.txtA standard file (RFC 9116) telling security researchers how to report vulnerabilities.
- Not published
Security headers 5 of 7
- HSTSpresent
- CSPpresent
- Framingpresent
- No sniffingpresent
- Referrerpresent
- Permissionsmissing
- Isolationmissing
Response
200 OK245 ms from CMHDNS lookup71 ms
200 instructorphp.com245 ms
DNSConnect (TCP + TLS)Waiting for the replyFrom Cloudflare's CMH data center
Response headers
- server
- nginx
- content-type
- text/html; charset=utf-8
- transfer-encoding
- chunked
- connection
- close
- vary
- Accept-Encoding
- cache-control
- max-age=0, must-revalidate, no-cache, no-store, private
- date
- Mon, 12 Oct 2026 16:03:58 GMT
- pragma
- no-cache
- expires
- Fri, 01 Jan 1990 00:00:00 GMT
- content-security-policy
default-src 'self'; base-uri 'self'; object-src 'none'; frame-ancestors 'self'; form-action 'self'; script-src 'self' 'nonce-48IoYoxzUW1fTi15Q3AVberQdZMKdaXqJy7TrKYV' 'unsafe-eval' https://buttons.github.io; style-src 'self' 'unsafe-inline'… Show all
default-src 'self'; base-uri 'self'; object-src 'none'; frame-ancestors 'self'; form-action 'self'; script-src 'self' 'nonce-48IoYoxzUW1fTi15Q3AVberQdZMKdaXqJy7TrKYV' 'unsafe-eval' https://buttons.github.io; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com https://cdnjs.cloudflare.com; font-src 'self' https://fonts.gstatic.com https://cdnjs.cloudflare.com data:; img-src 'self' data:; connect-src 'self'; frame-src https://buttons.github.io- referrer-policy
- strict-origin-when-cross-origin
- strict-transport-security
- max-age=86400
- set-cookie
XSRF-TOKEN=eyJpdiI6IlhGVE14Rk5DQXpIOVBtejQyTUs0L2c9PSIsInZhbHVlIjoiQ0JTLytNK1AxOWFRN3Y5VUlUMmd5YnNDZGJEc3ZLaEt5REFONk0xQlEyTzVnRzUrSC9hZHlRNzEyK3hrczlpOXdpR2JvYU51LzV3bFQzRUNpRWRCNWdISVNmL3hrV3VYdjJrN0Z1akhOOTdYeWNjeGRXeGJlVCtYbStxOE1wYzEiL… Show all
XSRF-TOKEN=eyJpdiI6IlhGVE14Rk5DQXpIOVBtejQyTUs0L2c9PSIsInZhbHVlIjoiQ0JTLytNK1AxOWFRN3Y5VUlUMmd5YnNDZGJEc3ZLaEt5REFONk0xQlEyTzVnRzUrSC9hZHlRNzEyK3hrczlpOXdpR2JvYU51LzV3bFQzRUNpRWRCNWdISVNmL3hrV3VYdjJrN0Z1akhOOTdYeWNjeGRXeGJlVCtYbStxOE1wYzEiLCJtYWMiOiIwNGI5M2RiYTZlMzI0MTQzMjQ0ODFmNGRiMDA5ZjJiZDFhMDFmM2M3MjM0ZjcyYjYyNTQzZTFhMjg0MmIzZDI0IiwidGFnIjoiIn0%3D; expires=Mon, 12 Oct 2026 18:03:58 GMT; Max-Age=7200; path=/; domain=instructorphp.com; secure; samesite=lax- set-cookie
instructor_for_php_session=eyJpdiI6Ikx3RTlBNTltS0pRRitNaWx1S1dDcUE9PSIsInZhbHVlIjoiamp0dVlCRXpWdjZRSVM2bm5vdGU3ZGVkU2JHZHkzS3lKZHJPcVc4c2kxVExmcmZZT3VCZzFPZTBHNG9GUVROMC82bjZHWlpnekFWdXdDR2JVK3dwMHAwZDdXY29RWUhhTVNnRlh4YmNCTjlKRzVpRVZpMW5WY… Show all
instructor_for_php_session=eyJpdiI6Ikx3RTlBNTltS0pRRitNaWx1S1dDcUE9PSIsInZhbHVlIjoiamp0dVlCRXpWdjZRSVM2bm5vdGU3ZGVkU2JHZHkzS3lKZHJPcVc4c2kxVExmcmZZT3VCZzFPZTBHNG9GUVROMC82bjZHWlpnekFWdXdDR2JVK3dwMHAwZDdXY29RWUhhTVNnRlh4YmNCTjlKRzVpRVZpMW5WY1YvRCtEaHBsdVciLCJtYWMiOiJkZjJlMWIyODEyYzI1OTA0ZjE3YzNlYjM0YjYzZjI4N2Q1MGM2NzQ2NzEzYmY1MGQ5M2QxYTA4ZmNlMDBmMGU2IiwidGFnIjoiIn0%3D; expires=Mon, 12 Oct 2026 18:03:58 GMT; Max-Age=7200; path=/; domain=instructorphp.com; secure; httponly; samesite=lax- x-frame-options
- SAMEORIGIN
- x-xss-protection
- 1; mode=block
- x-content-type-options
- nosniff
- content-encoding
- gzip
Details
Network
- IPv4
- 66.228.55.197
- Reverse DNSThe hostname this address points back to (its PTR record).
- 66-228-55-197.ip.linodeusercontent.com
- ASNThe autonomous system number of the network that announces this address.
- AS63949
- Operator
- Akamai (Linode)
- HostingFrom the provider's own published list of its address ranges.
- LinodeRichardson
- PrefixThe block of addresses announced over BGP that contains this address.
- 66.228.48.0/21
- RPKIWhether a signed record (ROA) authorizes this network to announce this prefix.
- Valid
- VisibilityHow many bgp.tools peers carry this announcement.
- 2,817 peers
- Type
- Content
- Registry
- ARIN
Location
- Country
- United States
- Region
- Texas
- City
- Richardson
- Coordinates
- 32.9482° N, 96.7297° W
- Accuracy
- Within about 20 km
- Time zone
- America/ChicagoUTC-5
- Local time
- 11:03
- Continent
- North America
Registration
RDAP- Registrar
- Dynadot Inc
- Registered
- Jun 12, 20242 years ago
- Expires
- Jun 12, 2027in 7 months
- Updated
- May 28, 2026
- StatusRegistry flags on the domain, such as locks that stop unauthorized transfers or changes.
- Transfer locked
- DNSSECDNSSEC signs DNS answers so they can't be forged on the way to you.
- Unsigned
- Name servers
- ns1.linode.comns2.linode.comns3.linode.comns4.linode.comns5.linode.com
- Registrant
- Redacted for privacy
Jun 12, 2024243 days leftJun 12, 2027
Website
Page
Instructor for PHP
- Language
- English
Built with
- CloudFrom the provider's published address ranges.
- Linode · Richardson
- Server
- nginxserver header “nginx”
Tech stack
Built with Each entry says what gave it away: a response header, a cookie's name, an asset's path or file name, or markup the tool leaves in the page. Versions are checked against endoflife.date's support schedules and, for JavaScript packages, OSV's vulnerability database, which carries GitHub's security advisories.
Hosting
- Linode · Richardson
Linode address range
Server
- nginx
server header “nginx”
UI
- Alpine.js
x-data attributes
- Livewire
wire:* attributes
Styling
- Tailwind CSS
93 Tailwind CSS class names
Fonts
- Inter
from Google Fonts
Build
- Vite
hashed module in /assets/
How it's made
- RenderingPrerendered pages are built ahead of time and served as files. Pages rendered on each request are built by server code for every visitor. Pages drawn in the browser arrive nearly empty and depend on JavaScript, which most AI crawlers don't run. Islands are interactive parts in otherwise static HTML.
- Rendered on each requestCache-Control: max-age=0, must-revalidate, no-cache, no-store, private
- Cache-Control
- max-age=0, must-revalidate, no-cache, no-store, private
- HTML
- 150.6 KB · sent gzip-compressed
- Scripts
- 3 files1 from other sites · 1 modules
Code from other sites Scripts a page loads from another domain run with the same power as its own code: they can read what visitors type and change the page. heade.rs checks what the HTML loads, not what tag managers add once they run.
- Fonts
- Google Fonts
- Public CDNsOpen-source packages loaded straight from a public CDN. A floating version (@3, @latest or none) can change under the site without a deploy. Without an integrity attribute, the browser can't tell if the CDN's copy was tampered with.
- tabler-icons@3.21.0No integrity check
- Integrity checksSubresource Integrity: the script tag carries a hash of the file, so the browser refuses it if the other site changes it. Analytics and tag manager scripts change by design and can't carry one; pinned library files can.
- 0 of 1 script
Adding integrity attributes to those tags makes browsers refuse a tampered copy.
AI & agents
Open to AI crawlers
robots.txt lets every AI crawler in.
Crawlers
Allows allTrainingSearchOn request
They visit a page when someone asks an assistant about it. ChatGPT's, Perplexity's, Meta's and Amazon's treat robots.txt as advisory;
Anthropic's and Mistral's follow it.
OpenAIGPTBotallowedOAI-SearchBotallowedChatGPT-Userallowed
AnthropicClaudeBotallowedClaude-SearchBotallowedClaude-Userallowed
GoogleGoogle-ExtendedallowedGooglebotallowed—
Microsoft—bingbotallowed—
AppleApplebot-ExtendedallowedApplebotallowed—
Perplexity—PerplexityBotallowedPerplexity-Userallowed
MetaMeta-ExternalAgentallowedMeta-WebIndexerallowedMeta-ExternalFetcherallowed
AmazonAmazonbotallowedAmzn-SearchBotallowedAmzn-Userallowed
MistralMistralAI-TrainingallowedMistralAI-IndexallowedMistralAI-Userallowed
OthersCCBotallowedBytespiderallowedDuckAssistBotallowed
- Can cite itThe AI products that can use the site in their answers: each answers from one crawler (OAI-SearchBot for ChatGPT search, Googlebot for AI Overviews, bingbot for Copilot), and robots directives on the front page, like noindex, nosnippet and noarchive, keep some out.
- ChatGPT searchClaudePerplexityAI OverviewsGeminiCopilotMeta AISiri
Reading
- Without JavaScriptText on the front page before any scripts run: what GPTBot, ClaudeBot, PerplexityBot and most agents read. Google, Bing and Apple's crawlers run scripts.
- 1,456 words
- MarkdownAgents like Claude Code, Cursor and OpenCode ask for Markdown in their Accept header. It's the page without its markup, so it costs them far fewer tokens.
- Not offered
- llms.txtA Markdown file listing a site's key pages for AI tools. Coding agents read it; search crawlers mostly don't.
- 17 links in 4 sectionsllms-full.txt too
- Structured dataschema.org JSON-LD in the page: facts about the site in a form machines read directly.
- None on the front page
Tools Ways an AI agent can do things on the site, not just read it: an MCP server that apps like Claude, ChatGPT and Cursor connect to, an API catalog, packaged agent skills, a shopping profile (UCP), or tools the page offers AI in the browser (WebMCP). heade.rs looks in the official MCP Registry and the files the site publishes under /.well-known/.
No MCP server, API catalog, agent skills, shopping profile or in-page tools found.