skyscanner.net
HTTPS & TLS
94/100A- HTTP/2 and HTTP/3HTTP/1.10/2
Only HTTP/1.1: no multiplexing, slower pages.
- HTTPS certificateLet's Encrypt10/10
HTTPS with a valid certificate from Let's Encrypt.
- Certificate expiry854/4
The certificate is valid for another 85 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 strengthECDSA P-2562/2
A strong key: ECDSA P-256.
- HTTP → HTTPS3013/3
http:// redirects straight to https://.
- HSTS1 year · preload4/4
HSTS tells browsers to use HTTPS only, for 1 year.
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).
- DKIMselector12/2
A DKIM key is published (selector selector1), so its mail can be signed.
Web & network
53/100D- Content Security Policy0/3
No Content Security Policy: an injected script runs with the page's full rights.
- Permissions-Policy0/0.5
No Permissions-Policy: embedded content may ask for camera, microphone or location.
- IPv60/4
skyscanner.net has no IPv6 address: IPv6-only networks reach it only through translation.
- X-Content-Type-Options2/2
X-Content-Type-Options: nosniff stops browsers guessing file types.
- Framing2/2
Other sites cannot frame its pages (clickjacking protection).
- Referrer-Policystrict-origin-when-cross-origin0.5/0.5
Referrer-Policy limits what other sites learn about where visitors came from.
- 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 Web Services: website, DNS3/5
Amazon Web Services runs both the website and the DNS: one outage there takes both down.
Who runs it
- Website
- Amazon Web Services
- Microsoft 365
Routes
- 76.223.16.0/20AS16509RPKI valid
Name servers
- ns-1333.awsdns-38.orgAmazon Route 53AS16509
- ns-1615.awsdns-09.co.ukAmazon Route 53AS16509
- ns-68.awsdns-08.comAmazon Route 53AS16509
- ns-769.awsdns-32.netAmazon Route 53AS16509
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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