SSL/TLS Certificate Lookup
Check a domain's SSL/TLS certificate — who issued it, when it expires, and whether the chain is trusted
u-book.de
SSL/TLS Certificate
SSL/TLS Certificate for u-book.de
Valid- Issued by (CA)
- Sectigo Limited
- Subject
- u-book.de
- Valid from
- Apr 20, 2026
- Valid until
- Nov 4, 2026 (56 days remaining)
- Public key
- RSA 2048-bit
- Serial
- 717742C9B2DA67A4EC535BE8EBC801DB
- SHA-256 fingerprint
- 9C:D7:4D:77:28:27:69:59:6B:64:EF:D2:36:BB:6C:45:00:6A:41:51:C5:E5:91:F9:69:BA:5B:6C:92:50:EC:8F
- Chain
- Sectigo Public Server Authentication CA DV R36 → Sectigo Public Server Authentication Root R46
Certificate Authority Authorization (CAA)
No CAA policy is published for this domain — any certificate authority may issue for it.
This certificate has been served since Aug 21, 2026.
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This is today's certificate. Turn on monitoring and we'll watch u-book.de continuously, notifying you the moment anything moves across all three signals:
Uptime
We visit the site from multiple regions worldwide and email you within minutes if it goes down, with a per-region breakdown so a real outage stands out from a regional blip.
DNS changes
We watch NS, MX, CAA, DNSSEC, CNAME and A/AAAA records, and identify the host, network, and ASN behind them, so a real migration or hijack stands out from routine noise.
TLS certificate
We warn you 30, 14, 7, and 1 days before it expires, and flag it if the issuing authority changes or the certificate is unexpectedly replaced.
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