xfinity.com

Name: xfinity.com Email Security Posture Assessment
Creator: RacterMX
License: https://creativecommons.org/licenses/by-nc/4.0/

Posture Score: 69/100

Scanned May 29, 2026 at 1:38 AM UTC

Identity

Attack Surface

Reputation

Identity Findings

No MX records found

The domain has no MX records and cannot receive email.

💡 Publish MX records pointing to your mail server(s).

critical

No NS records found

No nameserver records could be retrieved for this domain.

💡 Ensure NS records are properly configured at your registrar and in your zone file.

critical

Cannot check DNS consistency — no NS records

No nameserver records could be retrieved for consistency checking.

💡 Ensure NS records are properly configured.

high

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.xfinity.com

medium

BIMI logo may not be SVG Tiny PS

The logo URL returns Content-Type: . BIMI requires SVG Tiny PS format.

💡 Ensure the logo is in SVG Tiny PS format.

medium

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"

medium

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@xfinity.com").

low

ARC check skipped — no MX records

Cannot assess ARC support without MX records.

low

SPF record is valid

The SPF record is properly configured with valid syntax and within lookup limits.

pass

SPF record length OK (11 bytes)

SPF record is within safe DNS packet size limits.

pass

DKIM cryptographic configuration is compliant

No RFC 8301 compliance issues detected in DKIM key configuration.

pass

All external report destinations authorized

External DMARC report destinations have valid authorization records per RFC 7489 §7.1.

pass

Subdomains protected (sp=reject)

DMARC subdomain policy enforces quarantine or reject on unauthenticated subdomain mail.

pass

No deprecated DMARCbis tags present

The DMARC record does not use any tags deprecated in DMARCbis (pct, rf, ri).

pass

VMC URL is accessible

The BIMI VMC authority URL is reachable and returns a valid response.

pass

Meets bulk sender authentication requirements

Domain has SPF, DKIM, and DMARC — meeting Google/Yahoo 2024 bulk sender requirements for email authentication.

pass

IPv6 readiness is good

IPv6 records are present and properly configured.

pass

DNS TTL values follow best practices

All critical DNS record TTLs are within recommended ranges.

pass

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.

informational

DMARC alignment: adkim=r, aspf=r

DKIM alignment is relaxed, SPF alignment is relaxed.

informational

DMARCbis np tag absent

The DMARC record does not include the np (non-existent subdomain policy) tag. Consider adding np=reject to protect non-existent subdomains under DMARCbis.

informational

DMARCbis psd tag absent

The DMARC record does not include the psd (public suffix domain) indicator. Consider adding psd=n to explicitly identify this as an organizational domain.

informational

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.

informational

DANE check skipped — no MX records

Cannot check DANE/TLSA without MX records.

informational

Open relay check skipped — no MX records

Cannot test for open relay without MX records.

informational

SMTP compliance check skipped — no MX records

Cannot test SMTP compliance without MX records.

informational

Port exposure check skipped — no MX records

Cannot scan ports without MX records.

informational

STARTTLS downgrade check skipped — no MX records

Cannot test STARTTLS without MX records.

informational

RFC 8058 one-click unsubscribe assessment

No DKIM signing detected. RFC 8058 one-click unsubscribe requires DKIM-signed List-Unsubscribe headers.

informational

FCrDNS check skipped — no MX records

Cannot perform FCrDNS without MX records.

informational

SOA record parameters

Serial: 2015042249, Refresh: 7200s, Retry: 3600s, Expire: 604800s, Min TTL: 900s

informational

Attack Surface Findings

Non-routable IPv4 in public DNS: kibana.xfinity.com → 10.145.226.100

The subdomain kibana.xfinity.com resolves to non-routable IP 10.145.226.100, leaking internal network information.

💡 Remove non-routable IPs from public DNS or implement split-horizon DNS.

high

NSEC records enable zone walking

The domain uses NSEC records for DNSSEC authenticated denial of existence. NSEC records can be walked to enumerate all names in the zone, effectively disclosing the entire zone contents.

💡 Switch from NSEC to NSEC3 with opt-out to prevent zone enumeration. Use NSEC3 with a random salt and sufficient iterations.

high

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.

high

Microsoft Autodiscover accessible without authentication

The Autodiscover endpoint at https://autodiscover.xfinity.com/autodiscover/autodiscover.xml returns configuration data without requiring authentication. This exposes email server details to unauthenticated users.

💡 Configure the Autodiscover endpoint to require authentication before returning configuration data.

high

DNS ANY query returns 31 record(s)

The DNS server responds to ANY queries with 31 record(s), creating significant DNS amplification risk.

💡 Configure the DNS server to refuse or minimize ANY query responses per RFC 8482.

medium

NSEC used instead of NSEC3 (zone enumeration possible)

The domain uses NSEC records for authenticated denial of existence. NSEC allows zone walking.

💡 Migrate from NSEC to NSEC3 to prevent zone enumeration.

medium

All MX records resolve correctly

No dangling MX records detected — all MX hostnames resolve to valid IP addresses.

pass

Explicit MX records present

The domain has explicit MX records — no implicit A-record fallback delivery.

pass

9 subdomain(s) discovered for xfinity.com

Subdomains were enumerated via Certificate Transparency logs, DNS wordlist brute-forcing, and DNS record analysis.

informational

0 certificate(s) found in CT logs

Certificate Transparency logs contain 0 certificate(s) for xfinity.com and its subdomains. Each certificate reveals subdomain names.

informational

Mozilla Autoconfig endpoint detected

The Autoconfig endpoint at autoconfig.xfinity.com is publicly accessible.

informational

3 email SRV record(s) found

Email service SRV records expose mail server configuration for automatic client setup.

informational

DNSSEC is enabled

DNSKEY and/or DS records are present, indicating DNSSEC is configured.

informational

Reputation Findings

HSTS enabled but missing preload directive on xfinity.com

Strict-Transport-Security: max-age=31536000; includeSubDomains

💡 Add the "preload" directive to the HSTS header and submit the domain to hstspreload.org.

low

Not listed on any DNS blacklists

Domain and MX IPs checked against 55 DNSBLs — no listings found.

pass

security.txt present

Found security.txt at https://xfinity.com/.well-known/security.txt.

pass

TLS certificate valid for 139 days

Certificate for xfinity.com expires on 2026-10-15.

pass

Certificate issued by Sectigo Public Server Authentication CA OV R36

The certificate for xfinity.com is issued by a third-party CA.

pass

Signature algorithm: rsa-sha256

The certificate for xfinity.com uses an acceptable signature algorithm.

pass

RSA key: 2048 bits

The certificate for xfinity.com uses an adequate RSA key of 2048 bits.

pass

SCTs present in certificate

The certificate for xfinity.com contains Signed Certificate Timestamps.

pass

No weak ciphers detected

No known weak cipher suites detected on xfinity.com.

pass

No disposable email provider MX records

MX records for xfinity.com do not match known disposable email provider patterns.

pass

No wildcard MX records

No wildcard MX records detected for xfinity.com.

pass

TLD has good reputation

The .com TLD is not on known abuse watchlists.

pass

DMARC reporting destinations look legitimate

DMARC rua/ruf addresses do not point to known URL shortener services.

pass

MX records point to stable infrastructure

No MX records point to known dynamic DNS service domains.

pass

Strong TLS configuration on primary MX

Primary MX (mx2a1.comcast.net) uses TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 including Forward Secrecy.

pass

SMTP banner matches infrastructure identity

The SMTP banner (resimta-c2p-559906.sys.comcast.net) aligns with the MX hostname (mx1c1.comcast.net).

pass

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.

informational

Abuse contacts found for MX IPs

Abuse contact information retrieved via abusix.org DNS lookup.

informational

PhishTank — API key required

PhishTank phishing database check requires an API key.

informational

Sender Score — API key required

Sender Score reputation check requires an API key.

informational

Cisco Talos — API key required

Cisco Talos IP reputation check requires an API key.

informational

Could not connect to webmail.xfinity.com

HTTPS request to https://webmail.xfinity.com failed or timed out.

informational

WHOIS lookup failed

Could not retrieve WHOIS data for xfinity.com.

informational

Could not determine domain age

WHOIS creation date could not be parsed for xfinity.com.

informational

Bulletproof Hosting Detection — API key required

Checking IPs against known bulletproof hosting providers requires a threat intelligence API key.

informational

Threat Intelligence Feeds — API key required

Checking domain against threat intelligence feeds requires API keys (e.g., VirusTotal, AbuseIPDB).

informational

Typosquat detected: finity.com (has MX!), xinity.com (has MX!), xfinit.com (has MX!), sfinity.com (has MX!), xfiity.com

28 registered lookalike domain(s) that could be used for phishing against your brand. Showing top 5 of 28. Domains with MX records can send and receive email, making them high-risk phishing vectors.

informational

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: reject

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: reject

⚠️ 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: mx1a1.comcast.net

PTR record proves mail server legitimacy

MX: mx1a1.comcast.net Mail server at 96.103.145.163 → PTR Record No PTR record

⚠️ Mail server mx1a1.comcast.net (96.103.145.163) lacks a PTR record. Many receiving servers require matching forward and reverse DNS for spam prevention.

Mail Server Identity: mx1c1.comcast.net

PTR record proves mail server legitimacy

MX: mx1c1.comcast.net Mail server at 96.102.18.147 → PTR Record No PTR record

⚠️ Mail server mx1c1.comcast.net (96.102.18.147) lacks a PTR record. Many receiving servers require matching forward and reverse DNS for spam prevention.

Mail Server Identity: mx1h1.comcast.net

PTR record proves mail server legitimacy

MX: mx1h1.comcast.net Mail server at 96.102.157.181 → PTR Record No PTR record

⚠️ Mail server mx1h1.comcast.net (96.102.157.181) lacks a PTR record. Many receiving servers require matching forward and reverse DNS for spam prevention.

Mail Server Identity: mx2a1.comcast.net

PTR record proves mail server legitimacy

MX: mx2a1.comcast.net Mail server at 96.103.145.162 → PTR Record No PTR record

⚠️ Mail server mx2a1.comcast.net (96.103.145.162) lacks a PTR record. Many receiving servers require matching forward and reverse DNS for spam prevention.

Mail Server Identity: mx2c1.comcast.net

PTR record proves mail server legitimacy

MX: mx2c1.comcast.net Mail server at 96.102.18.146 → PTR Record No PTR record

⚠️ Mail server mx2c1.comcast.net (96.102.18.146) lacks a PTR record. Many receiving servers require matching forward and reverse DNS for spam prevention.

Mail Server Identity: mx2h1.comcast.net

PTR record proves mail server legitimacy

MX: mx2h1.comcast.net Mail server at 96.102.157.180 → PTR Record No PTR record

⚠️ Mail server mx2h1.comcast.net (96.102.157.180) lacks a PTR record. Many receiving servers require matching forward and reverse DNS for spam prevention.

Mail Server Reputation: mx1a1.comcast.net