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DNS Tool
Engineer's DNS Intelligence Report
Generated 2 Mar 2026, 01:58 UTC
Duration 22.0s
Version v26.28.35
Integrity 6ec48acd4d95c9d50fa7867de2b8b50a09327aee8281eb4e690337cf378bc7e83b19240ad5d3b600ba4649c7275e928521076368d44c3e55d605c3fd719988d1
Subject Domain
tuta.io

Engineer's DNS Intelligence Report

tuta.io
2 Mar 2026, 01:58 UTC · 22.0s ·v26.28.35 · SHA-3-512: 6ec4✱✱✱✱ Verify
Executive Methodology
Recon Mode Snapshot Re-analyze New Domain
Footprint 1 SaaS Service
DNS Security & Trust Posture
Risk Level: Low Risk
8 protocols configured, 1 not configured Why we go beyond letter grades
2 recommendations
Analysis Confidence (ICD 203)
MODERATE 63/100
Resolver agreement is inconsistent for some protocols, limiting confidence. Data currency and system maturity are adequate.
Accuracy 52% Currency 75/100 Maturity verified
Limiting factor: Resolver agreement is low for this scan — some protocols returned inconsistent results across resolvers
Intelligence Currency
Data Currency: Good 75/100
ICuAE Details
Currentness Excellent TTL Compliance Excellent Completeness Degraded Source Credibility Excellent TTL Relevance Degraded
DNS data is mostly current with minor gaps — good intelligence currency

The following DNS record TTLs deviate from recommended values. Incorrect TTLs can cause caching issues, slow propagation, or unnecessary DNS traffic.

Record Type Observed TTL Typical TTL Severity Context
SOA 10 minutes (600s) 1 hour (3600s) medium SOA TTL is below typical — observed 10 minutes (600s), typical value is 1 hour (3600s). Short TTLs increase DNS query volume but enable faster propagation. If you are preparing for a migration or need rapid failover, this may be intentional (RFC 1035 §3.2.1). For steady-state production, consider 3600 seconds per NIST SP 800-53 SI-18 relevance guidance. Use the TTL Tuner for profile-specific recommendations.
A 5 minutes (300s) 1 hour (3600s) high A TTL is below typical — observed 5 minutes (300s), typical value is 1 hour (3600s). Short TTLs increase DNS query volume but enable faster propagation. If you are preparing for a migration or need rapid failover, this may be intentional (RFC 1035 §3.2.1). For steady-state production, consider 3600 seconds per NIST SP 800-53 SI-18 relevance guidance. Use the TTL Tuner for profile-specific recommendations.
MX 10 minutes (600s) 1 hour (3600s) medium MX TTL is below typical — observed 10 minutes (600s), typical value is 1 hour (3600s). Short TTLs increase DNS query volume but enable faster propagation. If you are preparing for a migration or need rapid failover, this may be intentional (RFC 1035 §3.2.1). For steady-state production, consider 3600 seconds per NIST SP 800-53 SI-18 relevance guidance. Use the TTL Tuner for profile-specific recommendations.
CAA 10 minutes (600s) 1 hour (3600s) medium CAA TTL is below typical — observed 10 minutes (600s), typical value is 1 hour (3600s). Short TTLs increase DNS query volume but enable faster propagation. If you are preparing for a migration or need rapid failover, this may be intentional (RFC 1035 §3.2.1). For steady-state production, consider 3600 seconds per NIST SP 800-53 SI-18 relevance guidance. Use the TTL Tuner for profile-specific recommendations.
NS 10 minutes (600s) 1 day (86400s) high NS TTL is below typical — observed 10 minutes (600s), typical value is 1 day (86400s). Short TTLs increase DNS query volume but enable faster propagation. If you are preparing for a migration or need rapid failover, this may be intentional (RFC 1035 §3.2.1). For steady-state production, consider 86400 seconds per NIST SP 800-53 SI-18 relevance guidance. Use the TTL Tuner for profile-specific recommendations.
AAAA 5 minutes (300s) 1 hour (3600s) high AAAA TTL is below typical — observed 5 minutes (300s), typical value is 1 hour (3600s). Short TTLs increase DNS query volume but enable faster propagation. If you are preparing for a migration or need rapid failover, this may be intentional (RFC 1035 §3.2.1). For steady-state production, consider 3600 seconds per NIST SP 800-53 SI-18 relevance guidance. Use the TTL Tuner for profile-specific recommendations.
TXT 10 minutes (600s) 1 hour (3600s) medium TXT TTL is below typical — observed 10 minutes (600s), typical value is 1 hour (3600s). Short TTLs increase DNS query volume but enable faster propagation. If you are preparing for a migration or need rapid failover, this may be intentional (RFC 1035 §3.2.1). For steady-state production, consider 3600 seconds per NIST SP 800-53 SI-18 relevance guidance. Use the TTL Tuner for profile-specific recommendations.

Big Picture Questions

  • How often do you actually change this record? If it hasn’t changed in months, a short TTL is generating unnecessary DNS queries without any benefit.
  • Are you preparing for a migration or IP change? Short TTLs make sense temporarily — but should be raised back to 1 hour (3600s) once the change is complete.
  • Every DNS lookup adds 20–150ms of latency. With a 60s TTL, returning visitors trigger a fresh lookup every minute. With 3600s, they get cached responses for an hour — faster page loads, no extra infrastructure needed.
  • Google runs A records at ~30s because they operate a global anycast network and need to steer traffic dynamically. For a typical website without that infrastructure, copying those TTLs increases query volume with zero upside.
Tune TTL for tuta.io
Reference: NIST SP 800-53 SI-7 (Information Integrity) · RFC 8767 (Serve Stale) · RFC 1035 §3.2.1 (TTL semantics) DNS provider detected: AWS Route 53 — provider-specific RFC compliance notes are shown inline above where applicable.
Primary NS ns-660.awsdns-18.net
Serial 1
Admin awsdns-hostmaster.amazon.com
Provider AWS Route 53
Timer Value RFC 1912 Range
Refresh7200s1,200–43,200s (20 min – 12 hrs)
Retry900sFraction of Refresh
Expire1209600s1,209,600–2,419,200s (14–28 days)
Minimum (Neg. Cache)86400s300–86,400s (5 min – 1 day)
All SOA timer values are within RFC 1912 recommended ranges.

Independent RFC compliance assessment for AWS Route 53. Each finding cites the specific RFC section and reports what the engineering community consensus is. We report honestly — if a provider deviates from standards, we explain what they did differently and what the RFCs actually say.

Alias record TTLs fixed at 60s RFC 1035 §3.2.1

AWS Route 53 alias records pointing to AWS resources (ELB, CloudFront, S3, API Gateway) have a fixed TTL of 60 seconds that cannot be modified. Route 53 alias records are an AWS-specific extension — not part of standard DNS RFCs. They solve the CNAME-at-apex problem (RFC prohibits CNAME at zone apex) by appearing as A/AAAA records to resolvers. The 60-second TTL ensures fast failover but removes administrator TTL control.

Proprietary extension — not covered by DNS RFCs
This assessment is based on RFC specifications, provider documentation, and documented incidents from DNS engineering communities. DNS Tool does not have a commercial relationship with any provider listed.
Email Spoofing
Protected
Brand Impersonation
Not Setup
DNS Tampering
Protected
Certificate Control
Configured
Recommended
Upgrade DMARC policy from quarantine to reject (p=reject) for maximum spoofing protection, Add DMARC aggregate reporting (rua) for visibility into email authentication
Configured
SPF (hard fail), DMARC (quarantine, 100%), DKIM, MTA-STS, TLS-RPT, DANE, DNSSEC, CAA
Not Configured
BIMI
Priority Actions Achievable posture: Secure
Medium Add DMARC Aggregate Reporting

Add a rua= tag to receive aggregate DMARC reports. Without reporting, you cannot monitor authentication failures.

Aggregate reports show who is sending mail as your domain and whether it passes authentication.
TypeTXT
Host_dmarc.tuta.io (add to existing DMARC record)
Valuerua=mailto:dmarc-reports@tuta.io
RFC 7489 §7.1
Medium Upgrade DMARC to Reject

Your DMARC policy is set to quarantine. Upgrade to p=reject for maximum protection — reject instructs receivers to discard spoofed mail entirely rather than quarantining it.

A reject policy provides the strongest protection against domain spoofing.
TypeTXT
Host_dmarc.tuta.io (update existing DMARC record)
Valuev=DMARC1; p=reject; rua=mailto:dmarc-reports@tuta.io
RFC 7489 §6.3
Registrar (NS INFERENCE) INFERRED LIVE
Amazon Registrar
Inferred from NS records
Email Service Provider
Unknown
Moderately Protected
Web Hosting
Unknown
Where website is hosted
DNS Hosting OBSERVED
Amazon Route 53
Where DNS records are edited
Email Security Methodology Can this domain be impersonated by email? Unlikely SPF and DMARC quarantine policy enforced

SPF Record RFC 7208 §4 Verified

Does this domain declare who may send email on its behalf? Yes
Success -all 1/10 lookups

SPF valid with strict enforcement (-all), 1/10 lookups

v=spf1 include:spf.tutanota.de -all
RFC 7489 §10.1: -all may cause rejection before DMARC evaluation, preventing DKIM from being checked
RFC 7208 Conformant — This SPF record conforms to the syntax and semantics defined in RFC 7208 §4.
RFC Failure Mode: Unlike DMARC (where unknown tags are silently ignored per RFC 7489 §6.3), SPF with unrecognized mechanisms produces a PermError per RFC 7208 §4.6 — the record fails loudly rather than silently.
Related CVEs: CVE-2024-7208 (multi-tenant domain spoofing), CVE-2024-7209 (shared SPF exploitation), CVE-2023-51764 (SMTP smuggling bypasses SPF)
SPF hard fail (-all): compliance-strong, but can short-circuit DMARC. RFC 7489 notes that -all can cause some receivers to reject mail during the SMTP transaction — before DKIM is checked and before DMARC can evaluate the result. A message that would pass DMARC via DKIM alignment may be rejected prematurely. For most domains, ~all + DMARC p=reject is the strongest compatible posture — it allows every authentication method (SPF, DKIM, DMARC) to be fully evaluated before a decision is made.
DMARC enforcement is partial (quarantine). -all may preempt DKIM/DMARC evaluation at some receivers. Consider p=reject for full enforcement; ~all is more DMARC-compatible.

DMARC Policy RFC 7489 §6.3 Verified

Are spoofed emails rejected or quarantined? Quarantined, not rejected
Success p=quarantine

DMARC policy quarantine (100%) - good protection

v=DMARC1; p=quarantine; adkim=s
Alignment: SPF relaxed DKIM strict
No np= tag (DMARCbis) — non-existent subdomains inherit p= policy but adding np=reject provides explicit protection against subdomain spoofing
No aggregate reporting (rua) configured — you won't receive reports about authentication results and potential abuse
No forensic reporting (ruf) tag — this is correct. The absence of ruf= is not a gap. RFC 7489 §7.3 warns that forensic reports can expose PII (full message headers or bodies). Google, Microsoft, and Yahoo do not honour ruf= requests regardless. The DMARCbis draft (draft-ietf-dmarc-dmarcbis) has formally removed ruf= from the specification, confirming its deprecation. Omitting ruf= is the recommended modern practice. RFC 7489 §7.3 — Forensic Reports
RFC 7489 Present — DMARC record published per RFC 7489 §6.3.
Monitoring Posture Note: Quarantine sequesters authentication failures while preserving full DMARC forensic telemetry (RFC 7489 §7). Some organizations maintain quarantine rather than reject as a deliberate monitoring strategy — failed messages are processed and reported but sequestered from the inbox. See NIST SP 800-177 Rev. 1 for enforcement tradeoffs.
DMARCbis (Pending): draft-ietf-dmarc-dmarcbis will elevate DMARC to Standards Track, obsolete RFC 7489, replace pct= with t= (testing flag), add np= (non-existent subdomain policy), and mandate DNS tree walk for policy discovery instead of the Public Suffix List.
Related CVEs: CVE-2024-49040 (Exchange sender spoofing), CVE-2024-7208 (multi-tenant DMARC bypass)

DKIM Records RFC 6376 §3.6 Verified

Are outbound emails cryptographically signed? Yes — verified
Found

Found DKIM records for 2 selector(s)

s1._domainkey
v=DKIM1; k=rsa; h=sha256; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA4d/jridMLV9rZ/lBiDYA17BWKWIHnvLzCVGoFcOENqxLym8ro869rgp82mcxobr2kPyd+sfAS/REOoZ+pkf1wnyywQrf4r9i1O9Bnop4/WsRXTIfgKtaIOtwyhgsv9JH5KpxeQxHwl9CEHhqJuFJp808gbqRZt6PDp2YetB23EyJ5kp/jpn5/aCvVpC27+jnQH6NoYN8wNsC6cTSA1EhL1etUwJrZUwRtf8S2PIDJOm1/CUtc9a/d3sZk15LDtUUbODrQMrj5mzMzHPYp43MwLFRlvSa/O+xIx8esNxwnDa7PH6PZLB8lhtkY49/4ofKV5BQKMGmGmyn+rgYDHD8iwIDAQAB
s2._domainkey
v=DKIM1; k=rsa; h=sha256; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA4d/jridMLV9rZ/lBiDYA17BWKWIHnvLzCVGoFcOENqxLym8ro869rgp82mcxobr2kPyd+sfAS/REOoZ+pkf1wnyywQrf4r9i1O9Bnop4/WsRXTIfgKtaIOtwyhgsv9JH5KpxeQxHwl9CEHhqJuFJp808gbqRZt6PDp2YetB23EyJ5kp/jpn5/aCvVpC27+jnQH6NoYN8wNsC6cTSA1EhL1etUwJrZUwRtf8S2PIDJOm1/CUtc9a/d3sZk15LDtUUbODrQMrj5mzMzHPYp43MwLFRlvSa/O+xIx8esNxwnDa7PH6PZLB8lhtkY49/4ofKV5BQKMGmGmyn+rgYDHD8iwIDAQAB
RFC 6376 Conformant — DKIM keys and signatures conform to RFC 6376 §3.6 (Internet Standard).
Known Vulnerabilities: DKIM l= tag body length vulnerability (attacker appends unsigned content to signed mail), weak key exploitation (keys below 1024-bit are cryptographically breakable per RFC 6376 §3.3.3), DKIM replay attacks (re-sending legitimately signed messages at scale)

MTA-STS RFC 8461 §3 Verified

Can attackers downgrade SMTP to intercept mail? No — TLS enforced
Success ENFORCE Policy Verified

MTA-STS enforced - TLS required for 1 mail server(s)

v=STSv1; id=20190723;
Policy Details:
  • Mode: enforce
  • Max Age: 1 days (86400 seconds)
  • MX Patterns: mail.tutanota.de

MTA-STS policy enforcement is evaluated in Mail Transport Security below.

TLS-RPT RFC 8460 §3 Verified

Will failures in TLS delivery be reported? Yes — reports configured
Success

TLS-RPT configured - receiving TLS delivery reports

v=TLSRPTv1;rua=mailto:mta-sts-reports@tutanota.com
DANE / TLSA Verified Recon Methodology Can mail servers establish identity without a public CA? Yes
RFC 7672 §3 RFC 6698 §2 1/1 MX

DANE configured — TLSA records found for all 1 MX host

MX Host Usage Selector Match Certificate Data
mail.tutanota.de 3 DANE-EE (Domain-issued certificate) Full certificate SHA-256 d141f8f3a4aac2e4d2677aafcc723d8e5cc7b146e968c3aea348ed93996bbe6f
mail.tutanota.de 3 DANE-EE (Domain-issued certificate) Full certificate SHA-256 ae20396b8498eac32acecfdad63da655edbd6d6d79f7e1e0931852c8b738306d
Email Transport Security

Two mechanisms protect email in transit. DANE is the primary standard; MTA-STS is the alternative for domains that cannot deploy DNSSEC:

  • DNSSEC + DANE (RFC 7672) — Cryptographic chain of trust from DNS root to mail server certificate. Eliminates reliance on certificate authorities. No trust-on-first-use weakness. Requires DNSSEC.
  • MTA-STS (RFC 8461) — HTTPS-based policy requiring TLS for mail delivery. Works without DNSSEC but relies on CA trust and is vulnerable on first use (§10). Created for domains where “deploying DNSSEC is undesirable or impractical” (§2).
This domain deploys both DANE and MTA-STS — defense in depth. DANE provides cryptographic certificate binding via DNSSEC, while MTA-STS provides compatibility with senders that don't validate DNSSEC. Per RFC 8461, DANE takes precedence — MTA-STS must not override a failing DANE validation.

Industry trend: Microsoft Exchange Online enforces inbound DANE with DNSSEC (GA October 2024), and providers like Proton Mail and Fastmail also support DANE. Google Workspace does not support DANE and relies on MTA-STS. Both mechanisms coexist because DANE is backward-compatible — senders skip the check if the domain isn't DNSSEC-signed (RFC 7672 §1.3).

Brand Security Can this brand be convincingly faked? Likely DMARC quarantine flags but does not reject spoofed mail (RFC 7489 §6.3), and no BIMI brand verification — lookalike domains display identically in inboxes; CAA restricts certificate issuance (RFC 8659 §4) but visual brand faking remains open

BIMI BIMI Spec Verified Warning

Is the brand identity verified and displayed in inboxes? No

No BIMI record found

CAA RFC 8659 §4 Verified Success

Does this domain restrict who can issue TLS certificates? Yes

CAA configured - only Sectigo, Let's Encrypt can issue certificates

Authorized CAs: Sectigo Let's Encrypt
0 issue "sectigo.com"
0 issue "letsencrypt.org"
Since September 2025, all public CAs must verify domain control from multiple geographic locations (Multi-Perspective Issuance Corroboration, CA/B Forum Ballot SC-067). CAA records are now checked from multiple network perspectives before certificate issuance.
Vulnerability Disclosure Policy (security.txt) Is there a verified way to report security issues? No RFC 9116

No security.txt found

A security.txt file at /.well-known/security.txt provides security researchers with a standardized way to report vulnerabilities. See securitytxt.org for a generator.
AI Surface Scanner Beta Is this domain discoverable by AI — and protected from abuse? No

No AI governance measures detected

llms.txt llmstxt.org
Is this domain publishing AI-readable brand context? No
No llms.txt found
No llms-full.txt found
AI Crawler Governance (robots.txt) RFC 9309 IETF Draft
Are AI crawlers explicitly allowed or blocked? Not blocked
No AI crawler blocking observed — no blocking directives found in robots.txt
Content-Usage Directive IETF Draft
Does the site express AI content-usage preferences? Not Configured
No Content-Usage directive detected. The IETF AI Preferences working group is developing a Content-Usage: directive for robots.txt that lets site owners declare whether their content may be used for AI training and inference. This is an active draft, not yet a ratified standard.
Example: Add Content-Usage: ai=no to robots.txt to deny AI training, or Content-Usage: ai=allow to explicitly permit it. Without this directive, AI crawler behavior depends on individual crawler policies and User-agent rules.
AI Recommendation Poisoning
Is this site trying to manipulate AI recommendations? No
No AI recommendation poisoning indicators found
Hidden Prompt Artifacts
Is hidden prompt-injection text present in the source? No
No hidden prompt-like artifacts detected
Evidence Log (1 item)
TypeDetailSeverityConfidence
robots_txt_no_ai_blocks robots.txt found but no AI-specific blocking directives low Observed
Public Exposure Checks Are sensitive files or secrets exposed? No

No exposed secrets detected in public page source — same-origin, non-intrusive scan of publicly visible page source and scripts.

No exposed secrets, API keys, or credentials were detected in publicly accessible page source or scripts.
What type of scan is this?

This is OSINT (Open Source Intelligence) collection — we check the same publicly accessible URLs that any web browser could visit. No authentication is bypassed, no ports are probed, no vulnerabilities are exploited.

Is this a PCI compliance scan? No. PCI DSS requires scans performed by an Approved Scanning Vendor (ASV) certified by the PCI Security Standards Council. DNS Tool is not an ASV. If you need PCI compliance scanning, engage a certified ASV such as Qualys, Tenable, or Trustwave.

Is this a penetration test? No. Penetration testing involves active exploitation attempts against systems with authorization. Our checks are passive observation of publicly accessible resources — the same methodology used by Shodan, Mozilla Observatory, and other OSINT platforms.

DNS Server Security Hardened

No DNS server misconfigurations found on ns-1339.awsdns-39.org — Nmap NSE probes for zone transfer (AXFR), open recursion (RFC 5358), nameserver identity disclosure, and DNS cache snooping.

Check Result Detail
Zone Transfer (AXFR) Denied Zone transfer denied (correct configuration)
Open Recursion Disabled Recursion disabled (correct configuration)
Nameserver Identity Hidden No nameserver identity information disclosed
Cache Snooping Protected Cache snooping not possible (correct configuration)

Tested nameservers: ns-1339.awsdns-39.org, ns-492.awsdns-61.com, ns-660.awsdns-18.net, ns-1938.awsdns-50.co.uk

Delegation Consistency 1 Issue

Delegation consistency: 1 issue(s) found — Parent/child NS delegation alignment: DS↔DNSKEY, glue records, TTL drift, SOA serial sync.

Findings:
  • Could not retrieve NS TTL from parent zone

DS ↔ DNSKEY Alignment Aligned

DS Key TagDS AlgorithmDNSKEY Key TagDNSKEY Algorithm
47014 13 47014 13

Glue Record Completeness Complete

NameserverIn-BailiwickIPv4 GlueIPv6 GlueStatus
ns-1339.awsdns-39.org No N/A N/A OK
ns-1938.awsdns-50.co.uk No N/A N/A OK
ns-492.awsdns-61.com No N/A N/A OK
ns-660.awsdns-18.net No N/A N/A OK

NS TTL Comparison Drift

Child TTL: 600s Drift: 0s

SOA Serial Consistency Consistent

ns-1339.awsdns-39.org: 1
ns-1938.awsdns-50.co.uk: 1
ns-492.awsdns-61.com: 1
ns-660.awsdns-18.net: 1
Nameserver Fleet Matrix Healthy

Analyzed 4 nameserver(s) for tuta.io — Per-nameserver reachability, ASN diversity, SOA serial sync, and lame delegation checks.

Nameserver IPv4 IPv6 ASN / Operator UDP TCP AA SOA Serial
ns-1339.awsdns-39.org 205.251.197.59 2600:9000:5305:3b00::1 AS16509
Amazon.com, Inc. 		1
ns-660.awsdns-18.net 205.251.194.148 2600:9000:5302:9400::1 AS16509
Amazon.com, Inc. 		1
ns-1938.awsdns-50.co.uk 205.251.199.146 2600:9000:5307:9200::1 AS16509
Amazon.com, Inc. 		1
ns-492.awsdns-61.com 205.251.193.236 2600:9000:5301:ec00::1 AS16509
Amazon.com, Inc. 		1
Unique ASNs
1
Unique Operators
1
Unique /24 Prefixes
4
Diversity Score
Fair

1 ASN(s), 4 /24 prefix(es) — consider adding diversity

DNSSEC Operations Deep Dive 1 Issue

DNSSEC operational notes: 1 item(s) to review — KSK/ZSK differentiation, RRSIG expiry windows, NSEC/NSEC3 analysis, and rollover readiness.

Findings:
  • Single KSK with no CDS/CDNSKEY automation — manual rollover required

DNSKEY Inventory 3 Keys

RoleKey TagAlgorithmKey Size
ZSK 38075 ECDSA P-256/SHA-256 256 bits
ZSK 50228 ECDSA P-256/SHA-256 256 bits
KSK 47014 ECDSA P-256/SHA-256 256 bits

RRSIG Signatures 0 Signatures

No RRSIG records found.

Denial of Existence none

No NSEC or NSEC3 records detected.

Rollover Readiness Not_ready

Multiple KSKs:
CDS Published:
CDNSKEY Published:
Automation: none
Mail Transport Security Beta Is mail transport encrypted and verified? Yes Both MTA-STS and DANE enforce encrypted mail delivery

Transport encryption enforced via DNS policy (3 signal(s))

Policy Assessment Primary
  • MTA-STS policy in enforce mode requires encrypted transport (RFC 8461)
  • DANE/TLSA records published — mail servers pin TLS certificates via DNSSEC (RFC 7672)
  • TLS-RPT configured — domain monitors TLS delivery failures (RFC 8460)
Telemetry
TLS-RPT configured — domain receives reports about TLS delivery failures from sending mail servers (RFC 8460)
Reporting to: mailto:mta-sts-reports@tutanota.com
Live Probe Supplementary
Skipped — Remote probe failed (connection failed — probe may be offline) and local port 25 is blocked. Transport security is assessed via DNS policy records per NIST SP 800-177 Rev. 1.
Infrastructure Intelligence Who hosts this domain and what services power it? Direct

ASN / Network Success

Resolved 1 unique ASN(s) across 2 IP address(es)

ASNNameCountry
AS210909 DE
IPv4 Mappings:
185.205.69.12 → AS210909 (185.205.69.0/24)
IPv6 Mappings:
2a10:e000:1::12 → AS210909 (2a10:e000:1::/48)

Edge / CDN Success

Domain appears to use direct origin hosting

SaaS TXT Footprint Success 1 service

1 SaaS service detected via DNS TXT verification records

Detects SaaS services that leave DNS TXT verification records (e.g., domain ownership proofs). Does not detect all SaaS platforms — only those indicated by DNS.

ServiceVerification Record
Google Workspace google-site-verification=W1wGjtaeXf0wK5xyJjQI8Rcy9NEWjpcwxUhzSXK9B9I
Domain Security Methodology Can DNS responses be tampered with in transit? No DNSSEC signed and validated, cryptographic chain of trust verified

DNSSEC RFC 4033 §2 Verified Signed ECDSA P-256/SHA-256 Modern

DNSSEC fully configured and validated — AD (Authenticated Data) flag set by resolver 8.8.8.8 confirming cryptographic chain of trust from root to zone (RFC 4035 §3.2.3)

Algorithm Observation: ECDSA P-256/SHA-256 — MUST implement, recommended default (RFC 8624 §3.1)
All current DNSSEC algorithms use classical cryptography. Post-quantum DNSSEC standards are in active IETF development (draft-sheth-pqc-dnssec-strategy) but no PQC algorithms have been standardized for DNSSEC yet.
Chain of trust: Root → TLD → Domain. DNS responses are authenticated and tamper-proof.
AD Flag: Validated - Resolver (8.8.8.8) confirmed cryptographic signatures
DS Record (at registrar):
47014 13 2 B25B9B4FC9D805F1ED361B1EFA9B7BB8D2C105C8BBB1A002108547D1A19FF12B

NS Delegation Verified

4 nameserver(s) configured

Nameservers: ns-1339.awsdns-39.org ns-1938.awsdns-50.co.uk ns-492.awsdns-61.com ns-660.awsdns-18.net
Managed DNS
All 4 nameservers hosted by Amazon Route 53. Managed DNS provides reliable resolution with provider-maintained infrastructure.
DNS provider(s): Amazon Route 53
Multi-Resolver Verification Recon: Consensus reached - 5 resolvers (Cloudflare, Google, Quad9, OpenDNS, DNS4EU) agree on DNS records
Traffic & Routing Where does this domain's traffic actually terminate?

AIPv4 Address

185.205.69.12
Where the domain points for web traffic

AAAAIPv6 Address

2a10:e000:1::12
IPv6 ready

MXMail Servers

0 mail.tutanota.de.
Priority + mail server for email delivery

SRVServices

No SRV records
No service-specific routing configured
Web: Reachable (1 IPv4, 1 IPv6) Mail: 1 server Services: None
Subdomain Discovery RFC 6962 Recon LIVE What subdomains and infrastructure are exposed in certificate logs? 1 subdomains discovered
How did we find these?
3 unique certificates 1 current 0 expired Source: Certificate Transparency + DNS Intelligence
Subdomains discovered via CT logs (RFC 6962), DNS probing of common service names, and CNAME chain traversal.
Certificate Authority Diversity (1 CA observed across CT log history)
Certificate Authority Certs First Issued Last Issued Status
Let's Encrypt 3 2025-12-11 2026-03-01 Active
Subdomain Source Status Provider / CNAME Certificates First Seen Issuer(s)
mta-sts.tuta.io CT Log Current mta-sts.tutanota.com 2 2025-12-26T10:55:51 Let's Encrypt
Export Recon (CSV)
Δ Changes Detected: MTA-STS TLS-RPT Resolver ≠ Authoritative (TTL / CDN rotation / recent change)
Risk: Low - typically resolves within TTL
DNS Intelligence What does DNS look like right now — and what changed over time?
DNS Evidence Diff Side-by-side comparison
Resolver Records (Public DNS cache)
Authoritative Records (Source of truth)
A Synchronized 1 / 1 records
185.205.69.12
185.205.69.12
AAAA Synchronized 1 / 1 records
2a10:e000:1::12
2a10:e000:1::12
CAA RFC 8659 §4 Synchronized 2 / 2 records
0 issue "sectigo.com"
0 issue "letsencrypt.org"
0 issue "letsencrypt.org"
0 issue "sectigo.com"
DMARC _dmarc.tuta.io RFC 7489 §6.3 Synchronized 1 / 1 records
v=DMARC1; p=quarantine; adkim=s
v=DMARC1; p=quarantine; adkim=s
MTA-STS _mta-sts.tuta.io RFC 8461 §3 Propagating 1 / 1 records
v=STSv1; id=20190723;
_mta-sts.tutanota.com.
MX RFC 5321 Synchronized 1 / 1 records
0 mail.tutanota.de.
0 mail.tutanota.de.
NS RFC 1035 Synchronized 4 / 4 records
ns-660.awsdns-18.net.
ns-1339.awsdns-39.org.
ns-1339.awsdns-39.org.
ns-1938.awsdns-50.co.uk.
ns-1938.awsdns-50.co.uk.
ns-492.awsdns-61.com.
ns-492.awsdns-61.com.
ns-660.awsdns-18.net.
SOA RFC 1035 Synchronized 1 / 1 records
ns-660.awsdns-18.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
ns-660.awsdns-18.net. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
TLS-RPT _smtp._tls.tuta.io RFC 8460 §3 Propagating 1 / 1 records
v=TLSRPTv1;rua=mailto:mta-sts-reports@tutanota.com
_smtp._tls.tutanota.com.
TXT RFC 7208 §4 Synchronized 2 / 2 records
google-site-verification=W1wGjtaeXf0wK5xyJjQI8Rcy9NEWjpcwxUhzSXK9B9I
google-site-verification=W1wGjtaeXf0wK5xyJjQI8Rcy9NEWjpcwxUhzSXK9B9I
v=spf1 include:spf.tutanota.de -all
v=spf1 include:spf.tutanota.de -all
DNS History Timeline BETA
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DNS History Timeline BETA

When was a record added, removed, or changed — and could that change be the problem?

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Confirm Your Email Configuration

This tool analyzes DNS records, but to verify actual email delivery, send a test email to Red Sift Investigate. Their tool shows exactly how your emails arrive, including SPF/DKIM/DMARC pass/fail results in the headers.

DATA FRESHNESS & METHODOLOGY

All security-critical records (SPF, DMARC, DKIM, DANE/TLSA, DNSSEC, MTA-STS, TLS-RPT, BIMI, CAA) are queried live from authoritative nameservers and cross-referenced against 5 independent public DNS resolvers (Cloudflare, Google, Quad9, OpenDNS, DNS4EU) at the time of each analysis. No security verdict uses cached data.

Registrar data (RDAP) is cached for up to 24 hours because domain ownership and registration details change infrequently. Certificate Transparency logs (subdomain discovery via RFC 6962) are cached for 1 hour because CT entries are append-only historical records. Sections using cached data are marked with a CACHED badge; live queries show LIVE.

Intelligence Sources

This analysis used 4 DNS resolvers (consensus), reverse DNS (PTR), Team Cymru (ASN attribution), IANA RDAP (registrar), crt.sh (CT logs), and SMTP probing (transport). All using open-standard protocols.

Full List
Verify Report Integrity SHA-3-512 Has this report been altered since generation? Verify below

This cryptographic hash seals the analysis data, domain, timestamp, and tool version into a tamper-evident fingerprint. Any modification to the report data will produce a different hash. This is distinct from the posture hash (used for drift detection) — the integrity hash uniquely identifies this specific report instance.

6ec48acd4d95c9d50fa7867de2b8b50a09327aee8281eb4e690337cf378bc7e83b19240ad5d3b600ba4649c7275e928521076368d44c3e55d605c3fd719988d1
Evaluations reference 12 RFCs. Methods are reproducible using the verification commands provided. Results reflect DNS state at 2 Mar 2026, 01:58 UTC.
Download Raw Intelligence Download Checksum (.sha3)

Download the intelligence dump and verify its integrity, like you would a Kali ISO or any critical artifact. The SHA-3-512 checksum covers every byte of the download — deterministic serialization ensures identical hashes across downloads.

After downloading, verify with any of these commands:

Tip: cd ~/Downloads first (or wherever you saved the files).

OpenSSL + Sidecar (macOS, Linux, WSL) 
cat dns-intelligence-tuta.io.json.sha3 && echo '---' && openssl dgst -sha3-512 dns-intelligence-tuta.io.json
Python 3 (cross-platform) 
python3 -c "import hashlib; print(hashlib.sha3_512(open('dns-intelligence-tuta.io.json','rb').read()).hexdigest())"
sha3sum (coreutils 9+) 
sha3sum -a 512 dns-intelligence-tuta.io.json
Compare the output against the .sha3 file or the checksum API at /api/analysis/5219/checksum. Hash algorithm: SHA-3-512 (Keccak, NIST FIPS 202).

Every finding in this report is backed by DNS queries you can run yourself. These vetted one-liners reproduce the exact checks used to build this report for tuta.io. Our analysis adds multi-resolver consensus, RFC-based evaluation, and cross-referencing — but the underlying data is always independently verifiable. We are intelligence analysts, not gatekeepers.

DNS Records

Query A records (IPv4) RFC 1035 
dig +noall +answer tuta.io A
Query AAAA records (IPv6) RFC 1035 
dig +noall +answer tuta.io AAAA
Query MX records (mail servers) RFC 1035 
dig +noall +answer tuta.io MX
Query NS records (nameservers) RFC 1035 
dig +noall +answer tuta.io NS
Query TXT records RFC 1035 
dig +noall +answer tuta.io TXT

Email Authentication

Check SPF record RFC 7208 
dig +short tuta.io TXT | grep -i spf
Check DMARC policy RFC 7489 
dig +short _dmarc.tuta.io TXT
Check DKIM key for selector 's1' RFC 6376 
dig +short s1._domainkey.tuta.io TXT
Check DKIM key for selector 's2' RFC 6376 
dig +short s2._domainkey.tuta.io TXT

Domain Security

Check DNSSEC DNSKEY records RFC 4035 
dig +dnssec +noall +answer tuta.io DNSKEY
Check DNSSEC DS records RFC 4035 
dig +noall +answer tuta.io DS
Validate DNSSEC chain (requires DNSSEC-validating resolver) RFC 4035 
dig +dnssec +cd tuta.io A @1.1.1.1

Transport Security

Check TLSA record for mail.tutanota.de RFC 7672 
dig +noall +answer _25._tcp.mail.tutanota.de TLSA
Verify TLS certificate on primary MX (mail.tutanota.de) RFC 6698 
openssl s_client -starttls smtp -connect mail.tutanota.de:25 -servername mail.tutanota.de 2>/dev/null | openssl x509 -noout -subject -dates
Check MTA-STS DNS record RFC 8461 
dig +short _mta-sts.tuta.io TXT
Fetch MTA-STS policy file RFC 8461 
curl -sL https://mta-sts.tuta.io/.well-known/mta-sts.txt
Check TLS-RPT record RFC 8460 
dig +short _smtp._tls.tuta.io TXT

Brand & Trust

Check BIMI record BIMI Draft 
dig +short default._bimi.tuta.io TXT
Check CAA records (certificate authority authorization) RFC 8659 
dig +noall +answer tuta.io CAA

DNS Records

Check HTTPS/SVCB records RFC 9460 
dig +noall +answer tuta.io HTTPS

Domain Security

Check CDS/CDNSKEY automation records RFC 7344 
dig +noall +answer tuta.io CDS

Infrastructure Intelligence

RDAP domain registration lookup RFC 9083 
curl -sL 'https://rdap.org/domain/tuta.io' | python3 -m json.tool | head -50

Transport Security

Test STARTTLS on primary MX (mail.tutanota.de) RFC 3207 
openssl s_client -starttls smtp -connect mail.tutanota.de:25 -servername mail.tutanota.de </dev/null 2>/dev/null | head -5

Infrastructure Intelligence

Search Certificate Transparency logs RFC 6962 
curl -s 'https://crt.sh/?q=%25.tuta.io&output=json' | python3 -c "import json,sys; [print(e['name_value']) for e in json.load(sys.stdin)]" | sort -u | head -20
Check security.txt RFC 9116 
curl -sL https://tuta.io/.well-known/security.txt | head -20

AI Surface

Check for llms.txt 
curl -sI https://tuta.io/llms.txt | head -5
Check robots.txt for AI crawler rules 
curl -s https://tuta.io/robots.txt | grep -i -E 'GPTBot|ChatGPT|Claude|Anthropic|Google-Extended|CCBot|PerplexityBot'

Infrastructure Intelligence

ASN lookup for 185.205.69.12 (Team Cymru) 
dig +short 12.69.205.185.origin.asn.cymru.com TXT
Commands use dig, openssl, and curl — standard tools available on macOS, Linux, and WSL. Results may vary slightly due to DNS propagation timing and resolver caching.
Intelligence Confidence Audit Engine verified · 9/9 Evaluated
How confident are these results? Each protocol is independently verified against RFC standards. No self-awarded badges.
SPF
Verified 4851 runs
DKIM
Verified 4670 runs
DMARC
Verified 4835 runs
DANE/TLSA
Verified 4654 runs
DNSSEC
Verified 4832 runs
BIMI
Verified 4669 runs
MTA-STS
Verified 4672 runs
TLS-RPT
Verified 4674 runs
CAA
Verified 4666 runs
Maturity: Development → Verified → Consistent → Gold → Gold Master

Appendix: Verification Commands

The core DNS queries behind this report can be independently verified using these standard terminal commands (dig, openssl, curl). DNS Tool adds multi-resolver consensus, RFC-based evaluation, and cross-referencing on top of the raw data shown here.

DNS Records

Query A records (IPv4) (RFC 1035) 
dig +noall +answer tuta.io A
Query AAAA records (IPv6) (RFC 1035) 
dig +noall +answer tuta.io AAAA
Query MX records (mail servers) (RFC 1035) 
dig +noall +answer tuta.io MX
Query NS records (nameservers) (RFC 1035) 
dig +noall +answer tuta.io NS
Query TXT records (RFC 1035) 
dig +noall +answer tuta.io TXT

Email Authentication

Check SPF record (RFC 7208) 
dig +short tuta.io TXT | grep -i spf
Check DMARC policy (RFC 7489) 
dig +short _dmarc.tuta.io TXT
Check DKIM key for selector 's1' (RFC 6376) 
dig +short s1._domainkey.tuta.io TXT
Check DKIM key for selector 's2' (RFC 6376) 
dig +short s2._domainkey.tuta.io TXT

Domain Security

Check DNSSEC DNSKEY records (RFC 4035) 
dig +dnssec +noall +answer tuta.io DNSKEY
Check DNSSEC DS records (RFC 4035) 
dig +noall +answer tuta.io DS
Validate DNSSEC chain (requires DNSSEC-validating resolver) (RFC 4035) 
dig +dnssec +cd tuta.io A @1.1.1.1

Transport Security

Check TLSA record for mail.tutanota.de (RFC 7672) 
dig +noall +answer _25._tcp.mail.tutanota.de TLSA
Verify TLS certificate on primary MX (mail.tutanota.de) (RFC 6698) 
openssl s_client -starttls smtp -connect mail.tutanota.de:25 -servername mail.tutanota.de 2>/dev/null | openssl x509 -noout -subject -dates
Check MTA-STS DNS record (RFC 8461) 
dig +short _mta-sts.tuta.io TXT
Fetch MTA-STS policy file (RFC 8461) 
curl -sL https://mta-sts.tuta.io/.well-known/mta-sts.txt
Check TLS-RPT record (RFC 8460) 
dig +short _smtp._tls.tuta.io TXT

Brand & Trust

Check BIMI record (BIMI Draft) 
dig +short default._bimi.tuta.io TXT
Check CAA records (certificate authority authorization) (RFC 8659) 
dig +noall +answer tuta.io CAA

DNS Records

Check HTTPS/SVCB records (RFC 9460) 
dig +noall +answer tuta.io HTTPS

Domain Security

Check CDS/CDNSKEY automation records (RFC 7344) 
dig +noall +answer tuta.io CDS

Infrastructure Intelligence

RDAP domain registration lookup (RFC 9083) 
curl -sL 'https://rdap.org/domain/tuta.io' | python3 -m json.tool | head -50

Transport Security

Test STARTTLS on primary MX (mail.tutanota.de) (RFC 3207) 
openssl s_client -starttls smtp -connect mail.tutanota.de:25 -servername mail.tutanota.de </dev/null 2>/dev/null | head -5

Infrastructure Intelligence

Search Certificate Transparency logs (RFC 6962) 
curl -s 'https://crt.sh/?q=%25.tuta.io&output=json' | python3 -c "import json,sys; [print(e['name_value']) for e in json.load(sys.stdin)]" | sort -u | head -20
Check security.txt (RFC 9116) 
curl -sL https://tuta.io/.well-known/security.txt | head -20

AI Surface

Check for llms.txt 
curl -sI https://tuta.io/llms.txt | head -5
Check robots.txt for AI crawler rules 
curl -s https://tuta.io/robots.txt | grep -i -E 'GPTBot|ChatGPT|Claude|Anthropic|Google-Extended|CCBot|PerplexityBot'

Infrastructure Intelligence

ASN lookup for 185.205.69.12 (Team Cymru) 
dig +short 12.69.205.185.origin.asn.cymru.com TXT
Running Multi-Source Intelligence Audit

tuta.io

0s
DNS records — Cloudflare, Google, Quad9, OpenDNS, DNS4EU
Email auth — SPF, DMARC, DKIM selectors
DNSSEC chain of trust & DANE/TLSA
Certificate Transparency & subdomain discovery
SMTP transport & STARTTLS verification
MTA-STS, TLS-RPT, BIMI, CAA
Registrar & infrastructure analysis
Intelligence Classification & Interpretation

Every result includes terminal commands you can run to independently verify the underlying data. No proprietary magic.