Location
United States
Country level only
Domain
stackoverflow.com
Hosted by Cloudflare in the United States. Only the country is known, which is common for anycast and CDN addresses.
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.
AS13335Cloudflare
Cloudflare, Inc.
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 valid198.252.206.0/24
Seen by 3,363 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
Details
Network
- IPv4
- 198.252.206.1
- ASNThe autonomous system number of the network that announces this address.
- AS13335
- Operator
- Cloudflare, Inc.
- PrefixThe block of addresses announced over BGP that contains this address.
- 198.252.206.0/24
- RPKIWhether a signed record (ROA) authorizes this network to announce this prefix.
- Valid
- VisibilityHow many bgp.tools peers carry this announcement.
- 3,363 peers
- Type
- Content
- Registry
- ARIN
Location
Country level- Country
- United States
- Continent
- North America
Registration
RDAP- PopularityCloudflare Radar's ranking of domains by how often 1.1.1.1 users look them up.
- Top 2,000
- Registrar
- CSC Corporate Domains, Inc.
- Registered
- Dec 26, 200322 years ago
- Expires
- Feb 2, 2027in 3 months
- Updated
- Jan 29, 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
- damian.ns.cloudflare.comsureena.ns.cloudflare.com
- Registrant
- Redacted for privacy
Dec 26, 2003113 days leftFeb 2, 2027
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
- AS13335Cloudflare
Tracing from a probe near you with Globalping. Hop locations that its round-trip times rule out are left off the map.
Protected from spoofing
Mail that fails its checks is rejected under stackoverflow.com's DMARC policy, so forged mail doesn't reach inboxes.
- Receives mail
- Google Workspace
- Mail servers
- aspmx.l.google.comalt1.aspmx.l.google.comalt2.aspmx.l.google.com+2 more
- SPFLists the servers allowed to send mail for the domain. Receivers check it against the sending server.
- Soft-fails everything else10 of 10 DNS lookups · includes _spf.google.com, mailgun.org…
- DMARCTells receivers what to do with mail that fails SPF and DKIM: nothing (none), spam folder (quarantine) or reject.
- Rejectsends reports
- 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
Astackoverflow.com198.252.206.11 min
NSstackoverflow.comdamian.ns.cloudflare.com1 day
NSstackoverflow.comsureena.ns.cloudflare.com1 day
MXstackoverflow.com1 aspmx.l.google.com5 min
MXstackoverflow.com10 alt3.aspmx.l.google.com5 min
MXstackoverflow.com10 alt4.aspmx.l.google.com5 min
MXstackoverflow.com5 alt1.aspmx.l.google.com5 min
MXstackoverflow.com5 alt2.aspmx.l.google.com5 min
TXTstackoverflow.com"MS=ms52592611"3 min
TXTstackoverflow.com"ZOOM_verify_AbkNwz5bBl0eurcDKyhhuk"3 min
TXTstackoverflow.com"adobe-idp-site-verification=25ba5203f3687c9cd6ee3223ee5de1528917828d1da3ebd3bd9a44094cbfc4ac"3 min
TXTstackoverflow.com"anthropic-domain-verification-q70207=cKyy0llXkD10O4rDQpWz8tQ5K"3 min
TXTstackoverflow.com"apple-domain-verification=O9jlnJXAQ7sNSZqC"3 min
TXTstackoverflow.com"atlassian-domain-verification=byLeZgl3MIcfOqwWuMhq8Fhr/1zem/jIaouJegvDZbBKUU5OqhwDjdpkyYg5CTzm"3 min
TXTstackoverflow.com"cursor-domain-verification-sb0ayf=Pk6AyptQuTpzpcuSlfYGWloxv"3 min
TXTstackoverflow.com"docker-verification=d65aee54-9091-4ceb-b792-61f5d5804050"3 min
TXTstackoverflow.com"docusign=4262531d-29f4-4a62-9f33-ae9f66f5247b"3 min
TXTstackoverflow.com"google-site-verification=2Bi6SYw5skkRexdtdLPL2gpxeIhLxnYVqITVP9Htl3w"3 min
TXTstackoverflow.com"google-site-verification=ctogLnZNAdc_CXq8yOhODMLpmugGynjxKecKHDz4oL8"3 min
TXTstackoverflow.com"google-site-verification=o3EMam8yBGo1yEjyybIiZcOunGHOQKpo8JmOtp9n1BU"3 min
TXTstackoverflow.com"google-site-verification=rdWtMbplKjbRHGr2dNONfwkqithlUvjr3u6i8QEz_mo"3 min
TXTstackoverflow.com"ibmid=4e7cbbb3-5f12-40b4-96c7-5b064347b822"3 min
TXTstackoverflow.com"make-domain-verification=eec31159-f381-4f38-9d89-e59123dd023e"3 min
TXTstackoverflow.com"onetrust-domain-verification=0d9d67f856334905a54256085a5768b3"3 min
TXTstackoverflow.com"onetrust-domain-verification=e445562296a64c649ae3d520230b8c4c"3 min
TXTstackoverflow.com"openai-domain-verification=dv-GLNufzbWDzAq0fDXHD6jxeCK"3 min
TXTstackoverflow.com"profound-domain-verification-5p599x=hWudYd2Du6WOYOod5ko9Rwnp8"3 min
TXTstackoverflow.com"v=MCPv1; k=ed25519; p=VhBofO8RaYvTvHT7q5tTty+HQeCU8R6h5Y8k/sj20So="3 min
TXTstackoverflow.com"v=spf1 ip4:52.38.191.241 include:_spf.google.com include:mailgun.org include:sendgrid.net include:mail.zendesk.com include:spf.tipalti.com ~all"3 min
TXTstackoverflow.com"work-os-domain-verification-43a3e0=GoDUTSc5MMjDaiIC3s5yRKqMD"3 min
TXT_dmarc.stackoverflow.com"v=DMARC1; p=reject; pct=100; rua=mailto:dmarc-aggregates@stackoverflow.com; ruf=mailto:dmarc-forensics@stackoverflow.com; fo=1"5 min
CAAstackoverflow.com0 issue "comodoca.com"5 min
CAAstackoverflow.com0 issue "digicert.com; cansignhttpexchanges=yes"5 min
CAAstackoverflow.com0 issue "letsencrypt.org"5 min
CAAstackoverflow.com0 issue "pki.goog; cansignhttpexchanges=yes"5 min
CAAstackoverflow.com0 issue "sectigo.com"5 min
CAAstackoverflow.com0 issue "ssl.com"5 min
CAAstackoverflow.com0 issuewild "comodoca.com"5 min
CAAstackoverflow.com0 issuewild "digicert.com; cansignhttpexchanges=yes"5 min
CAAstackoverflow.com0 issuewild "letsencrypt.org"5 min
CAAstackoverflow.com0 issuewild "pki.goog; cansignhttpexchanges=yes"5 min
CAAstackoverflow.com0 issuewild "sectigo.com"5 min
CAAstackoverflow.com0 issuewild "ssl.com"5 min
CAAstackoverflow.com128 iodef "mailto:sysadmin-team@stackoverflow.com"5 min
HTTPSstackoverflow.com1 . alpn=h2 ipv4hint=198.252.206.12 min
HTTPS
Certificate
Valid- Issuer
- Let's Encrypt
- Issuing CA
- YE2
- Covers
- stackoverflow.com
- Also validOther unexpired certificates for this name, found in Certificate Transparency logs.
- 22 more certificates
Oct 6, 202684 days leftJan 4, 2027
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.
- Not sent
- 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
- Encrypted helloEncrypted Client Hello (ECH) hides which site you're visiting from anyone watching the connection.
- Not published
- CAADNS records naming the only certificate authorities allowed to issue certificates for the domain.
- Sectigo, DigiCert, Let's Encrypt, Google Trust Services, SSL.com
- security.txtA standard file (RFC 9116) telling security researchers how to report vulnerabilities.
- Not published
Security headers 6 of 7
- HSTSmissing
- CSPpresent
- Framingpresent
- No sniffingpresent
- Referrerpresent
- Permissionspresent
- Isolationpresent
Response
403 Forbidden6 ms from CMHDNS lookup3 ms
302 stackoverflow.com36 ms
403 stackoverflow.com/questions6 ms
DNSConnect (TCP + TLS)Waiting for the replyFrom Cloudflare's CMH data center
Response headers
- accept-ch
Sec-CH-UA-Bitness, Sec-CH-UA-Arch, Sec-CH-UA-Full-Version, Sec-CH-UA-Mobile, Sec-CH-UA-Model, Sec-CH-UA-Platform-Version, Sec-CH-UA-Full-Version-List, Sec-CH-UA-Platform, Sec-CH-UA, UA-Bitness, UA-Arch, UA-Full-Version, UA-Mobile, UA-Model,… Show all
Sec-CH-UA-Bitness, Sec-CH-UA-Arch, Sec-CH-UA-Full-Version, Sec-CH-UA-Mobile, Sec-CH-UA-Model, Sec-CH-UA-Platform-Version, Sec-CH-UA-Full-Version-List, Sec-CH-UA-Platform, Sec-CH-UA, UA-Bitness, UA-Arch, UA-Full-Version, UA-Mobile, UA-Model, UA-Platform-Version, UA-Platform, UA- cf-cache-status
- DYNAMIC
- cf-mitigated
- challenge
- cf-ray
- a49756f5d91e3f27-CMH
- connection
- close
- content-security-policy
default-src 'none'; script-src 'nonce-XcYtDffttlINvG5zTcUsRi' 'unsafe-eval' https://challenges.cloudflare.com; script-src-attr 'none'; style-src 'unsafe-inline'; img-src 'self' https://challenges.cloudflare.com; connect-src 'self' https://c… Show all
default-src 'none'; script-src 'nonce-XcYtDffttlINvG5zTcUsRi' 'unsafe-eval' https://challenges.cloudflare.com; script-src-attr 'none'; style-src 'unsafe-inline'; img-src 'self' https://challenges.cloudflare.com; connect-src 'self' https://challenges.cloudflare.com; frame-src 'self' https://challenges.cloudflare.com blob:; child-src 'self' https://challenges.cloudflare.com blob:; worker-src blob:; form-action http: https:; base-uri 'self'- content-type
- text/html; charset=UTF-8
- critical-ch
Sec-CH-UA-Bitness, Sec-CH-UA-Arch, Sec-CH-UA-Full-Version, Sec-CH-UA-Mobile, Sec-CH-UA-Model, Sec-CH-UA-Platform-Version, Sec-CH-UA-Full-Version-List, Sec-CH-UA-Platform, Sec-CH-UA, UA-Bitness, UA-Arch, UA-Full-Version, UA-Mobile, UA-Model,… Show all
Sec-CH-UA-Bitness, Sec-CH-UA-Arch, Sec-CH-UA-Full-Version, Sec-CH-UA-Mobile, Sec-CH-UA-Model, Sec-CH-UA-Platform-Version, Sec-CH-UA-Full-Version-List, Sec-CH-UA-Platform, Sec-CH-UA, UA-Bitness, UA-Arch, UA-Full-Version, UA-Mobile, UA-Model, UA-Platform-Version, UA-Platform, UA- cross-origin-embedder-policy
- require-corp
- cross-origin-opener-policy
- same-origin
- cross-origin-resource-policy
- same-origin
- date
- Mon, 12 Oct 2026 16:04:19 GMT
- origin-agent-cluster
- ?1
- permissions-policy
- accelerometer=(),camera=(),clipboard-read=(),clipboard-write=(),geolocation=(),gyroscope=(),hid=(),magnetometer=(),microphone=(),payment=(),publickey-credentials-get=(),screen-wake-lock=(),serial=(),sync-xhr=(),usb=(),xr-spatial-tracking=*
- referrer-policy
- same-origin
- server
- cloudflare
- server-timing
- chlray;desc="a49756f5dac33401"
- set-cookie
__cf_bm=HDtv_JelCW7jchSal4yxbTRpFBznKx0fp.vOnxNBaxA-1791821059.4987419-1.0.1.1-xSazWzJwopxAZPa.PVbDCqSIRSYGfNR8q9PBijLpHnFIoHA7WA35bU1S5_JPeotV4QZe4BJmD5K.70AgYT.fHYt0mzYhmJvJ9UrpHmxK_D5gvXkT.gOPleuJmQgcK0QT0T1nD_UjXW4cBmBxN.LQY1YhQR8POyItU… Show all
__cf_bm=HDtv_JelCW7jchSal4yxbTRpFBznKx0fp.vOnxNBaxA-1791821059.4987419-1.0.1.1-xSazWzJwopxAZPa.PVbDCqSIRSYGfNR8q9PBijLpHnFIoHA7WA35bU1S5_JPeotV4QZe4BJmD5K.70AgYT.fHYt0mzYhmJvJ9UrpHmxK_D5gvXkT.gOPleuJmQgcK0QT0T1nD_UjXW4cBmBxN.LQY1YhQR8POyItUw_DpnYJOpI; HttpOnly; SameSite=None; Secure; Path=/; Domain=stackoverflow.com; Expires=Mon, 12 Oct 2026 16:34:19 GMT- transfer-encoding
- chunked
- vary
- accept-encoding
- x-content-type-options
- nosniff
- x-dns-prefetch-control
- off
- x-frame-options
- SAMEORIGIN
Website
Page
403The site's bot protection turned away heade.rs's request (403), so the page couldn't be read.
Built with
- CDN
- Cloudflarecf-ray header
Tech stack
Cloudflare's bot check answered instead of the page, so only what the response headers and cookies say is shown here.
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.
CDN & edge
- Cloudflare
cf-ray header
Bot protection
- Cloudflare Bot Management
__cf_bm cookie
AI & agents
Turns away automated requests
Its bot protection refused heade.rs (403), so agents that fetch pages for people probably get the same answer.
Crawlers
No robots.txtTrainingSearchOn 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
It's on Cloudflare, which can also block AI crawlers at its edge whatever robots.txt says.
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.
- Page couldn't be read
- 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.
- Page couldn't be read
- llms.txtA Markdown file listing a site's key pages for AI tools. Coding agents read it; search crawlers mostly don't.
- Not published
- Structured dataschema.org JSON-LD in the page: facts about the site in a form machines read directly.
- Page couldn't be read
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/.
Couldn't check: the site didn't answer heade.rs's requests for its agent files.