booking.com
HTTPS & TLS
100/100A+- HTTPS certificateDigiCert Inc10/10
HTTPS with a valid certificate from DigiCert Inc.
- Certificate expiry1914/4
The certificate is valid for another 191 days.
- TLS versionTLS 1.34/4
Negotiates TLS 1.3, the current protocol: faster handshakes, forward secrecy always.
- Old protocols3/3
Refuses the retired TLS 1.0 and 1.1.
- Key strengthRSA 20482/2
A strong key: RSA 2048.
- HTTP → HTTPS3013/3
http:// redirects straight to https://.
- HSTS2 years · preload4/4
HSTS tells browsers to use HTTPS only, for 2 years.
- HTTP/2 and HTTP/3HTTP/22/2
HTTP/2.
DNS
64/100D- DNSSEC0/3
Not signed with DNSSEC: a forged DNS answer for the domain cannot be told from the real one.
- CAA records0/2
No CAA records: any certificate authority may issue certificates for the domain.
- Name servers44/4
4 name servers for the domain.
- Name servers answer4/45/5
Every name server answers for the domain, with the same version of the zone.
- MTA-STS0/2
No MTA-STS: mail to the domain can be read in transit by stripping its encryption.
- TLS reporting0/0.5
No TLS reporting: failed encrypted deliveries go unnoticed.
- SPF-all5/5
SPF lists the servers allowed to send its mail and rejects the rest (-all).
- DMARCreject7/7
DMARC tells receivers to reject mail that fakes the domain (p=reject).
- DKIMs12/2
A DKIM key is published (selector s1), so its mail can be signed.
Web & network
25/100F- Content Security Policy0/3
No Content Security Policy: an injected script runs with the page's full rights.
- X-Content-Type-Options0/2
No X-Content-Type-Options: browsers may run an upload as a script.
- Framing0/2
Any site can show its pages in a frame, which enables clickjacking.
- Referrer-Policy0/0.5
No Referrer-Policy of its own (browsers' default applies).
- Permissions-Policy0/0.5
No Permissions-Policy: embedded content may ask for camera, microphone or location.
- IPv60/4
www.booking.com has no IPv6 address: IPv6-only networks reach it only through translation.
- RPKIvalid4/4
The route to the website is RPKI-valid: networks can reject hijacked announcements of it.
Dependencies
60/100D- DNS providersAmazon Route 533/5
All DNS is with one provider (Amazon Route 53): an outage there takes the domain offline, as Dyn's did in 2016.
- One company for everythingAmazon CloudFront: website, DNS3/5
Amazon CloudFront runs both the website and the DNS: one outage there takes both down.
Who runs it
- Website
- Amazon CloudFront
- Proofpoint
Routes
- 54.192.35.0/24AS16509RPKI valid
Name servers
- ns-1288.awsdns-33.orgAmazon Route 53AS16509
- ns-1959.awsdns-52.co.ukAmazon Route 53AS16509
- ns-508.awsdns-63.comAmazon Route 53AS16509
- ns-716.awsdns-25.netAmazon Route 53AS16509
README badge
Show the grade in your README or docs; it updates when the domain is graded again.
[](https://skycisa.com/grade/booking.com)Compare with…
What is graded
A valid certificate (an invalid one means F), its expiry against its lifetime, TLS 1.3, no TLS 1.0/1.1 (else at most B), http:// sent straight to https://, HSTS, HTTP/2.
At least two name servers that all answer and agree, DNSSEC, CAA records, and a registration that is not about to expire.
SPF, a DMARC policy that rejects forgeries (none means at most B), MTA-STS and TLS reporting for domains that take mail, DKIM at common selectors.
Content Security Policy, nosniff, framing protection, Referrer- and Permissions-Policy, IPv6, and an RPKI-valid route (invalid means at most C).
DNS from more than one provider, and the website, DNS and email not all with one company.
A+ 95–100 · A 85–94 · B 75–84 · C 65–74 · D 50–64 · F below 50