Skip to content
Pricing RU Sign In
RU

SNI: Definition, Use Cases, and Examples

By · Updated
TL;DR:

SNI (Server Name Indication) is a TLS extension that lets the client specify a hostname at the start of the TLS handshake. Without SNI, a single IP could not serve multiple HTTPS sites with different certificates. Required for virtual hosting. Supported by all modern browsers and SSL libraries.

Try it now — free →

What is SNI

SNI (Server Name Indication) is a TLS extension that lets the client specify a hostname at the start of the TLS handshake. Without SNI, a single IP could not serve multiple HTTPS sites with different certificates. Required for virtual hosting. Supported by all modern browsers and SSL libraries.

Check SNI online

Open tool →

Related guides

CertificateExpiry, issuer, domains (SAN)
ChainIntermediate and root CA validation
TLS ProtocolTLS version and cipher suite
VulnerabilitiesHeartbleed, POODLE, weak ciphers

Why teams trust us

TLS 1.3
supported
Full
CA chain check
<2s
result
30/14/7
days-to-expiry alerts

How it works

1

Enter domain

2

TLS chain verified

3

Expiry date & vulnerabilities

What Does the SSL Check Cover?

SSL/TLS is the encryption protocol that protects data between the browser and server. Our tool analyzes the certificate, chain of trust, TLS version, and knownvulnerabilities.

Certificate Details

Issuer, validity period, signature algorithm, covered domains (SAN), and validation type (DV/OV/EV).

Chain of Trust

Full chain verification: from leaf certificate through intermediates to root CA.

TLS Analysis

Protocol version (TLS 1.2/1.3), cipher suites, Perfect Forward Secrecy (PFS) support.

Expiry Alerts

Set up a monitor — get Telegram and email alerts 30/14/7 days before expiration.

DV vs OV vs EV Certificates

DV (Domain Validation)
  • Confirms domain ownership only
  • Issued in minutes automatically
  • Free via Let's Encrypt
  • Suitable for most websites
  • Most common certificate type
OV / EV
  • Organization (OV) or Extended Validation (EV)
  • Issued in 1-5 business days
  • Costs $50 to $500/year
  • For finance, e-commerce, government sites
  • Increases user trust

Who uses this

DevOps

SSL certificate monitoring

Security

TLS config audit

SEO

HTTPS as ranking factor

E-commerce

customer trust

Common Mistakes

❌
Expired certificateBrowsers block sites with expired SSL. Set up auto-renewal or monitoring.
❌
Incomplete certificate chainWithout intermediate CA, some browsers and bots cannot verify the certificate.
❌
Mixed content on HTTPS siteHTTP resources on an HTTPS page — the browser lock icon disappears, reducing trust.
❌
Using TLS 1.0/1.1Legacy TLS versions have known vulnerabilities. Use TLS 1.2+ or 1.3.
❌
Domain mismatch in certificateThe certificate must cover all site domains, including www and subdomains.

Best Practices

✓
Set up auto-renewalLet's Encrypt + certbot with cron — certificate renews automatically every 60-90 days.
✓
Enable HSTSStrict-Transport-Security header forces browsers to always use HTTPS.
✓
Use TLS 1.3TLS 1.3 is faster (1-RTT handshake) and safer — legacy ciphers removed.
✓
Monitor expiration datesCreate a monitor on Enterno.io — get notified well before expiration.
✓
Verify chain after renewalAfter certificate renewal, confirm that intermediate certificates are installed.

Get more with a free account

SSL certificate monitoring, check history and alerts 30 days before expiry.

Sign up free

Related tools

DNS LookupSecurity CheckPageSpeedMixed Content

Learn more

How-to

Glossary

Research

Errors

Alternatives

Frequently Asked Questions

Do I need SNI?

See the use-case section above. For a quick check, use our online form.

Start monitoring for free

Sign up and get access to API, monitoring and notifications

Create Account API Documentation