Identity
0
F
xundns.com
Posture Score: 36/100
Scanned May 29, 2026 at 7:06 AM UTC
Score History
Attack Surface
47
Reputation
62
Identity Findings
No SPF record found
The domain has no SPF record, allowing anyone to send email as this domain.
💡 Publish an SPF TXT record (e.g. "v=spf1 include:_spf.google.com -all").
No DMARC record found
The domain has no DMARC record, providing no policy for handling unauthenticated email.
💡 Publish a DMARC TXT record at _dmarc.xundns.com (e.g. "v=DMARC1; p=reject; rua=mailto:dmarc@xundns.com").
Does not meet bulk sender requirements
Google and Yahoo require all bulk senders to have SPF+DKIM, DMARC, and one-click unsubscribe. Issues: Neither SPF nor DKIM is configured (at least one required); No DMARC record published (required since Feb 2024); SPF not published (recommended alongside DKIM)
💡 Publish SPF, DKIM, and DMARC records. Implement RFC 8058 one-click unsubscribe for marketing mail.
FCrDNS failure: no PTR for 122.14.229.0 (mx3.feishu.cn)
The IP 122.14.229.0 has no PTR record. Forward-confirmed reverse DNS requires a PTR that resolves back to the IP.
💡 Configure a PTR record for the IP that matches the mail server hostname.
FCrDNS failure: no PTR for 101.126.58.225 (mx3.feishu.cn)
The IP 101.126.58.225 has no PTR record. Forward-confirmed reverse DNS requires a PTR that resolves back to the IP.
💡 Configure a PTR record for the IP that matches the mail server hostname.
FCrDNS failure: no PTR for 101.126.58.225 (mx2.feishu.cn)
The IP 101.126.58.225 has no PTR record. Forward-confirmed reverse DNS requires a PTR that resolves back to the IP.
💡 Configure a PTR record for the IP that matches the mail server hostname.
FCrDNS failure: no PTR for 122.14.229.0 (mx2.feishu.cn)
The IP 122.14.229.0 has no PTR record. Forward-confirmed reverse DNS requires a PTR that resolves back to the IP.
💡 Configure a PTR record for the IP that matches the mail server hostname.
Zone contains undelegated nameservers
The zone advertises nameservers not present in the parent delegation: u1.xundns.com, u2.xundns.com
💡 Remove unauthorized NS records from the zone or add them to the parent delegation at the registrar.
No DKIM records found
No DKIM records were found after probing 56 common selectors. The domain may use a custom selector not discoverable via external scan.
💡 Configure DKIM signing and publish the public key at <selector>._domainkey.xundns.com
No PTR record for MX IP: 122.14.229.0
The IP 122.14.229.0 (for mx3.feishu.cn) has no reverse DNS record.
💡 Configure a PTR record for the mail server IP.
No PTR record for MX IP: 101.126.58.225
The IP 101.126.58.225 (for mx3.feishu.cn) has no reverse DNS record.
💡 Configure a PTR record for the mail server IP.
No PTR record for MX IP: 101.126.58.225
The IP 101.126.58.225 (for mx2.feishu.cn) has no reverse DNS record.
💡 Configure a PTR record for the mail server IP.
No PTR record for MX IP: 122.14.229.0
The IP 122.14.229.0 (for mx2.feishu.cn) has no reverse DNS record.
💡 Configure a PTR record for the mail server IP.
No MTA-STS record found
Without MTA-STS, mail transport encryption cannot be enforced and is vulnerable to downgrade attacks.
💡 Publish a _mta-sts TXT record and host a policy file at https://mta-sts.xundns.com/.well-known/mta-sts.txt
STARTTLS without MTA-STS or DANE protection
STARTTLS alone is vulnerable to downgrade attacks. Neither MTA-STS nor DANE is configured to enforce encryption.
💡 Deploy MTA-STS and/or DANE to protect against STARTTLS stripping attacks.
Generic ISP PTR hostname: ec2-52-220-106-220.ap-southeast-1.compute.amazonaws.com
The PTR record for 52.220.106.220 appears to be a generic ISP hostname, which can harm deliverability.
💡 Set a meaningful PTR record like mail.xundns.com
Generic ISP PTR hostname: ec2-52-220-106-220.ap-southeast-1.compute.amazonaws.com
The PTR record for 52.220.106.220 appears to be a generic ISP hostname, which can harm deliverability.
💡 Set a meaningful PTR record like mail.xundns.com
SOA expire value too short
The SOA expire value is 86400s (<604,800s / 7 days). Secondary nameservers may stop serving the zone prematurely.
💡 Increase the SOA expire value to at least 604800 seconds (7 days).
No CAA records found
No CAA records are configured. Any certificate authority can issue certificates for this domain.
💡 Add CAA records to restrict certificate issuance. Example: 0 issue "letsencrypt.org"
No TLS-RPT record found
Without TLS-RPT, you will not receive reports about TLS negotiation failures.
💡 Publish a _smtp._tls TXT record (e.g. "v=TLSRPTv1; rua=mailto:tls-reports@xundns.com").
ARC support not detected
No evidence of ARC (Authenticated Received Chain) support on MX servers. Forwarded messages may lose authentication.
💡 Consider enabling ARC signing on your mail servers to preserve authentication through forwarding.
Shared IP 122.14.229.0 used by multiple MX servers
The IP 122.14.229.0 is shared across 2 MX hostnames, reducing redundancy.
💡 Use unique IP addresses for each MX server for better redundancy.
Shared IP 52.220.106.220 used by multiple MX servers
The IP 52.220.106.220 is shared across 2 MX hostnames, reducing redundancy.
💡 Use unique IP addresses for each MX server for better redundancy.
Shared IP 101.126.58.225 used by multiple MX servers
The IP 101.126.58.225 is shared across 2 MX hostnames, reducing redundancy.
💡 Use unique IP addresses for each MX server for better redundancy.
DKIM cryptographic configuration is compliant
No RFC 8301 compliance issues detected in DKIM key configuration.
SMTP security checks passed
No open relay, VRFY/EXPN, or banner disclosure issues detected.
SMTP RFC 5321 compliance checks passed
The mail server accepts postmaster@ and abuse@ and uses a valid FQDN in EHLO.
IPv6 readiness is good
IPv6 records are present and properly configured.
DNS responses are consistent across all nameservers
All authoritative nameservers return consistent answers with proper AA flags.
DNS TTL values follow best practices
All critical DNS record TTLs are within recommended ranges.
DKIM2 not detected
No DKIM key record with v=2 was found across common selectors. DKIM2 is an emerging standard and not yet widely deployed.
REQUIRETLS not advertised
The primary MX does not advertise REQUIRETLS (RFC 8689). This is an emerging standard — MTA-STS and DANE provide adequate TLS enforcement for most deployments.
No DANE/TLSA records found
DANE is not configured for any MX server. This is optional but provides strong certificate binding.
No BIMI record found
BIMI is not configured. Your brand logo will not display in supporting email clients.
Open mail ports on mx3.feishu.cn
Detected open mail-related ports: 25
RFC 8058 one-click unsubscribe assessment
No DKIM signing detected. RFC 8058 one-click unsubscribe requires DKIM-signed List-Unsubscribe headers.
MX IP network diversity
MX IPs span 3 different /16 networks, providing good diversity.
SOA record parameters
Serial: 437896, Refresh: 3600s, Retry: 600s, Expire: 86400s, Min TTL: 600s
Attack Surface Findings
AXFR zone transfer allowed on u1.xundns.com
The nameserver u1.xundns.com allows AXFR zone transfers, exposing the complete zone contents to anyone. This is the most severe enumerability issue.
💡 Restrict AXFR transfers on u1.xundns.com to authorized secondary nameservers only using allow-transfer ACLs.
AXFR zone transfer allowed on u2.xundns.com
The nameserver u2.xundns.com allows AXFR zone transfers, exposing the complete zone contents to anyone. This is the most severe enumerability issue.
💡 Restrict AXFR transfers on u2.xundns.com to authorized secondary nameservers only using allow-transfer ACLs.
Domain enumerability: high
The domain is highly enumerable. Zone transfers, NSEC zone walking, or a combination of factors make it easy to discover all DNS records.
💡 Restrict zone transfers, use NSEC3 instead of NSEC, consider wildcard certificates to reduce CT log exposure, and implement rate limiting on DNS queries.
Non-mail domain has no SPF record
This domain has no MX records (does not receive mail) but also has no SPF record. Without "v=spf1 -all", attackers can spoof this domain in phishing emails.
💡 Publish "v=spf1 -all" to explicitly declare this domain sends no mail.
HINFO record exposes system information
An HINFO record for xundns.com reveals hardware/OS details: CPU=, OS=. This aids attacker reconnaissance.
💡 Remove the HINFO record from public DNS. HINFO records are rarely needed and expose unnecessary system details.
LOC record exposes geographic location
A LOC record for xundns.com reveals the physical location of infrastructure. This aids targeted attacks.
💡 Remove the LOC record from public DNS unless geographic information is intentionally published.
No MX records — A-record fallback active
The domain has no MX records but has an A record. Per RFC 5321, mail servers will attempt delivery to the A record IP. This domain may be silently accepting mail without SPF/DKIM/DMARC protection.
💡 If this domain should not receive mail, publish a Null MX record (RFC 7505): "0 ." as the MX. If it should receive mail, add proper MX records.
DNS ANY query returns 1 record(s)
The DNS server responds to ANY queries with 1 record(s). The low record count limits amplification risk, but ANY responses still aid reconnaissance.
💡 Configure the DNS server to refuse or minimize ANY query responses per RFC 8482.
RP record exposes responsible person
An RP (Responsible Person) record for xundns.com reveals contact information: 307527401113129984.url.xunurl.com.. This can be used for social engineering.
💡 Remove the RP record if the contact information is not intended to be public.
No internal information leakage detected
No non-routable IP addresses or internal references were found in public DNS records.
No email autodiscovery endpoints detected
No Microsoft Autodiscover, Mozilla Autoconfig, or email SRV records were found.
5 subdomain(s) discovered for xundns.com
Subdomains were enumerated via Certificate Transparency logs, DNS wordlist brute-forcing, and DNS record analysis.
0 certificate(s) found in CT logs
Certificate Transparency logs contain 0 certificate(s) for xundns.com and its subdomains. Each certificate reveals subdomain names.
NSEC3 authenticated denial of existence
The domain uses NSEC3 with -1 iteration(s) and salt '-'.
DNSSEC is enabled
DNSKEY and/or DS records are present, indicating DNSSEC is configured.
Reputation Findings
Listed on dnsbl-3.uceprotect.net
101.126.58.225 (mx2.feishu.cn) is listed on blacklist dnsbl-3.uceprotect.net (response: 127.0.0.2).
💡 Visit the dnsbl-3.uceprotect.net website to request delisting. Investigate the root cause (compromised account, open relay, spam) before requesting removal.
Could not retrieve TLS certificate
Failed to connect to xundns.com:443 or retrieve the peer certificate.
💡 Ensure the domain has a valid TLS certificate installed and port 443 is accessible.
SMTP banner mismatch: n105-033-231
The SMTP banner identifies as 'n105-033-231' but the MX hostname is 'mx1.feishu.cn' and PTR resolves to 'ec2-52-220-106-220.ap-southeast-1.compute.amazonaws.com'. Microsoft and other receivers flag this mismatch as suspicious infrastructure.
💡 Configure the SMTP server banner to match the MX hostname or PTR record (mx1.feishu.cn).
Domain valid for 457 days
Domain xundns.com expires on 2027-08-29.
Domain transfer and delete locks enabled
Domain xundns.com has clientTransferProhibited and clientDeleteProhibited locks.
No disposable email provider MX records
MX records for xundns.com do not match known disposable email provider patterns.
Domain is 6847 days old
Domain xundns.com was registered 2007-08-29.
No wildcard MX records
No wildcard MX records detected for xundns.com.
TLD has good reputation
The .com TLD is not on known abuse watchlists.
MX records point to stable infrastructure
No MX records point to known dynamic DNS service domains.
Strong TLS configuration on primary MX
Primary MX (mx1.feishu.cn) uses TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 including Forward Secrecy.
Google Safe Browsing DNS check — no flag detected
DNS-based Safe Browsing lookup returned no results. Full verification requires the Google Safe Browsing API key.
Abuse contacts found for MX IPs
Abuse contact information retrieved via abusix.org DNS lookup.
PhishTank — API key required
PhishTank phishing database check requires an API key.
Sender Score — API key required
Sender Score reputation check requires an API key.
Cisco Talos — API key required
Cisco Talos IP reputation check requires an API key.
Could not connect to xundns.com
HTTPS request to https://xundns.com failed or timed out.
Could not connect to webmail.xundns.com
HTTPS request to https://webmail.xundns.com failed or timed out.
WHOIS registration data
Registrar: GoDaddy.com, LLC | Created: 2007-08-29 | Expires: 2027-08-29 | Updated: 2026-05-11
WHOIS privacy protection enabled
Domain xundns.com has WHOIS privacy/redaction enabled.
Bulletproof Hosting Detection — API key required
Checking IPs against known bulletproof hosting providers requires a threat intelligence API key.
Threat Intelligence Feeds — API key required
Checking domain against threat intelligence feeds requires API keys (e.g., VirusTotal, AbuseIPDB).
Typosquat detected: xunns.com (has MX!), zundns.com (has MX!), sundns.com (has MX!), xindns.com (has MX!), xunsns.com (has MX!)
11 registered lookalike domain(s) that could be used for phishing against your brand. Showing top 5 of 11. Domains with MX records can send and receive email, making them high-risk phishing vectors.
Dependency Chains
DMARC Authentication Chain (SPF)
DMARC uses SPF to verify that emails come from authorized servers
SPF Record
SPF record found and configured
→
DMARC Policy
DMARC policy missing
⚠️ DMARC policy is missing. Even with SPF configured, you lack the policy layer that tells receiving servers what to do with authentication failures.
DMARC Authentication Chain (DKIM)
DMARC uses DKIM to verify that emails have not been tampered with
DKIM Signature
DKIM signature missing
→
DMARC Policy
DMARC policy missing
⚠️ DKIM signature is missing. DMARC relies on DKIM to verify email integrity and prevent tampering. Without DKIM, DMARC alignment will fail for cryptographic verification.
Mail Server Identity: mx3.feishu.cn
PTR record proves mail server legitimacy
MX: mx3.feishu.cn
Mail server at 101.126.58.225
→
PTR Record
No PTR record
⚠️ Mail server mx3.feishu.cn (101.126.58.225) lacks a PTR record. Many receiving servers require matching forward and reverse DNS for spam prevention.
Mail Server Identity: mx1.feishu.cn
PTR record proves mail server legitimacy
MX: mx1.feishu.cn
Mail server at 52.220.106.220
→
PTR Record
Reverse DNS: ec2-52-220-106-220.ap-southeast-1.compute.amazonaws.com
Mail Server Identity: mx2.feishu.cn
PTR record proves mail server legitimacy
MX: mx2.feishu.cn
Mail server at 101.126.58.225
→
PTR Record
No PTR record
⚠️ Mail server mx2.feishu.cn (101.126.58.225) lacks a PTR record. Many receiving servers require matching forward and reverse DNS for spam prevention.
Mail Server Reputation: mx3.feishu.cn
RBL check ensures server is not blacklisted
MX: mx3.feishu.cn
Mail server at 101.126.58.225
→
RBL Status
Not blacklisted
Mail Server Reputation: mx1.feishu.cn
RBL check ensures server is not blacklisted
MX: mx1.feishu.cn
Mail server at 52.220.106.220
→
RBL Status
Not blacklisted
Mail Server Reputation: mx2.feishu.cn
RBL check ensures server is not blacklisted
MX: mx2.feishu.cn
Mail server at 101.126.58.225
→
RBL Status
Not blacklisted
Enforced Encryption Chain
MTA-STS enforces TLS encryption to prevent man-in-the-middle attacks
TLS Support
Mail servers support TLS encryption
→
MTA-STS Policy
MTA-STS not configured
⚠️ MTA-STS policy is missing. Even with TLS support, you lack the enforcement layer that prevents attackers from stripping encryption (downgrade attacks).
Brand Identity Chain
BIMI displays your logo in email clients, but requires DMARC enforcement
DMARC Enforcement
DMARC not enforced (p=none or missing)
→
BIMI Record
BIMI not configured
⚠️ DMARC is not enforced. BIMI requires a DMARC policy of "quarantine" or "reject" to prove you have strong email authentication. Without enforcement, email clients will not display your logo.
TLS Monitoring Chain
TLS-RPT provides reports about TLS connection failures
TLS Support
Mail servers support TLS encryption
→
TLS-RPT Reporting
TLS-RPT not configured
⚠️ TLS-RPT is not configured. Without TLS reporting, you have no visibility into TLS connection failures that may be impacting email delivery.
Security Checks
MX Records
✓
SPF Record
✓
DKIM Record
✗
DMARC Policy
✗
BIMI Record
✗
CAA Records
✗
DNSSEC
✗
MTA-STS
✗
TLS-RPT
✗
Embed Badge
Display your domain's security grade on your website or README:
<img src="https://scan.ractermx.com/badge/xundns.com.svg" alt="Email Security Grade">
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