duo.vn website report
DUO ONLINE CORPORATION
Last scanned
Overall score
Fair
About duo.vn
duo.vn is a website.
Score profile
Top issues to fix
10 issues found · 4 high priority
TLS certificate expires in -727 days
SecurityRenew now (or enable auto-renewal) — an expired certificate blocks visitors with a full-page browser warning.
Missing Content-Security-Policy header
SecurityAdd a CSP to control which sources can run scripts — the strongest single defense against XSS.
Missing meta description
SEOAdd a ~150-character meta description to control your search-result snippet and lift click-through rate.
No H1 heading found
SEOAdd exactly one H1 describing the page's main topic — it anchors the document outline for search engines and screen readers.
Missing X-Content-Type-Options header
SecurityAdd X-Content-Type-Options: nosniff to stop MIME-sniffing attacks.
Missing X-Frame-Options header
SecurityAdd X-Frame-Options (or a CSP frame-ancestors rule) to prevent clickjacking via hidden iframes.
+4 more issues — details in the sections below.
Technology stack
duo.vn is built with jQuery, Nginx and Meta Pixel.
Hosting & DNS
- IP address
- —
- ASN
- —
- IPv6
- Not supported
- HTTP
- HTTP/2
Show DNS record values
TXT record contents are not republished; only their count is shown.
Security
duo.vn serves a certificate that fails verification (expired) and sets 1 of 6 recommended security headers.
Security headers1 of 6 set
- HSTSForces HTTPS
- CSPBlocks injected scripts
- X-Frame-OptionsStops clickjacking
- X-Content-TypeStops MIME sniffing
- Referrer-PolicyLimits URL leakage
- Permissions-PolicyRestricts browser features
TLS certificate
- Names covered
- 1
- Cookies set
- 0
Email security
duo.vn scores F for email security, with SPF and no DMARC policy.
- SPFWeak
Marks unlisted senders as suspicious (~all) but does not reject them.
- DMARCNot set
No DMARC policy: forged mail is not told to be rejected.
- MTA-STSNot set
Not published; mail to this domain can be downgraded to plaintext.
- BIMINot set
Not published (optional).
Performance & carbon
duo.vn scores 100/100 for performance, with an estimated load time of 0.7 s. A visit emits an estimated 0.00 g of CO2 (grade A+).
Page weight
- HTML 2.5 KB
- JavaScript 342 B
- Est. load
- 723 ms
- Response
- 723 ms
- Scripts / CSS
- 6 / 3
Carbon per visitA+
0.00 g CO2 per uncached view
Estimate from the Sustainable Web Design model. HTML, JavaScript and CSS only; images, video and fonts are not measured. Treat it as a lower bound for comparing pages, not an audit.
SEO & accessibility
duo.vn scores 55/100 for SEO and 90/100 for accessibility, with 6 SEO issues to fix.
Heading structure
No H1 found.
Image alt text
0 images · 0 without alt text · 0 lazy-loaded
Links
SEO issues6
- Missing meta description
- Missing canonical link
- No H1 heading found
- No structured data (JSON-LD) found
- robots.txt not found
- sitemap.xml not found
Accessibility issues1
- No H1 heading found
Technical details
Page metadata, social tags, crawl files and scan information.
Meta tags
- Title
- DUO ONLINE CORPORATION
- Description
- Canonical
- Language
- en
- Robots meta
Crawl files
- robots.txt
- Not found
- Disallow rules
- 0
- sitemap.xml
- Not found
- URLs in sitemap
- 0
Structured data
No JSON-LD types declared.
- Microdata items
- 0
- RDFa items
- 0
Scan
- Final URL
- https://duo.vn
- HTTP status
- 200
- Redirects
- https://duo.vn
- Scanned
- Aug 24, 2026, 1:23 PM
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<a href="https://sitegraph.tech/site/duo-vn"><img src="https://sitegraph.tech/badge/duo-vn.svg" alt="duo.vn on SiteGraph" width="190" height="20" /></a>See something wrong on this report? Request a correction or ask for something to be removed.
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Frequently asked questions about duo.vn
- What is duo.vn?
- duo.vn is a website.
- What technology does duo.vn use?
- duo.vn is built with jQuery, Nginx and Meta Pixel.
- Is duo.vn secure?
- duo.vn serves a certificate that fails verification (expired) and sets 1 of 6 recommended security headers.
- Is duo.vn protected against email spoofing?
- duo.vn scores F for email security, with SPF and no DMARC policy.
- What is duo.vn's overall score?
- duo.vn has an overall SiteGraph score of 68/100, combining SEO (55), performance (100), security (35) and accessibility (90).
Open Graph & Twitter