DNS & Email Security Report for slack.com

• A record presentcritical

  6 A record(s) found

• AAAA record presentrecommended

  No AAAA records

• MX records presentrecommended

  5 MX record(s) found

• NS records presentcritical

  4 NS record(s) found

• SOA record presentcritical

  SOA record found

• Multiple nameserversrecommended

  4 nameservers configured ✓

• SOA serial formatinfo

  Serial 1 (valid, managed DNS format)

• SOA timers validinfo

  Refresh: 7200s ✓, Retry: 900s ✓, Expire: 1209600s ✓

• No lame nameserversinfo

  4 NS all responding ✓

• Glue records presentinfo

  No glue needed

• WWW record configuredinfo

  A record matches apex

• MX servers have PTR recordsinfo

  8 MX IPs all have PTR records ✓

• MX servers have FCrDNSinfo

  8 MX IPs have forward-confirmed reverse DNS ✓

• DNSSEC signedrecommended

  DNSSEC is enabled ✓

• DNSSEC validation OKcritical

  DNSSEC validates correctly ✓

• NSEC3 RFC 9276 compliantrecommended

  Not applicable (domain uses NSEC or is not DNSSEC-signed)

• RRSIG signatures validrecommended

  RRSIG signature expires in 0 days — renewal needed

• Modern DNSSEC algorithmoptional

  ECDSA P-256 (algorithm 13) — modern ✓

• DS digest algorithm modernrecommended

  DS digest: SHA-256 — modern ✓

• DNSKEY algorithm secureoptional

  DNSKEY: ECDSA P-256 — modern ✓

• RRSIG TTL saferecommended

  A TTL (60s) exceeds RRSIG validity (0d). Cached records may outlive signatures

• Chain of trust completecritical

  Complete chain: DNSKEY + DS + RRSIG ✓

• Website reachable via IPv6recommended

  No IPv6 for website. Add AAAA record pointing to your IPv6 address

• Mail servers reachable via IPv6recommended

  5/5 MX server(s) with IPv6 ✓

• Nameservers reachable via IPv6recommended

  4/4 NS server(s) with IPv6 ✓

• SPF record presentcritical

  v=spf1 include:_spf.qualtrics.com include:mail.zendesk.com include:_spfextra.slack.com -all

• SPF syntax validcritical

  SPF syntax is correct ✓

• SPF policy strict (-all)recommended

  SPF uses -all (hard fail) ✓

• DKIM foundrecommended

  DKIM selector: smtpapi ✓

• DMARC record presentrecommended

  v=DMARC1;p=reject;fo=1:d:s;pct=100;rua=mailto:[email protected],mailto:[email protected];ruf=mailto:[email protected]

• DMARC policy quarantine or betterrecommended

  DMARC policy: reject ✓

• DMARC policy rejectoptional

  DMARC policy: reject ✓

• BIMI record presentoptional

  No BIMI record. Add TXT at default._bimi with logo URL (requires DMARC p=quarantine+)

• BIMI configuration validoptional

  No BIMI configured

• MTA-STS record presentoptional

  No MTA-STS. Add TXT at _mta-sts and host policy at /.well-known/mta-sts.txt

• MTA-STS policy enforcedoptional

  MTA-STS not configured

• MX records validcritical

  5 MX record(s) ✓

• MX domains use DNSSECrecommended

  0/2 MX domain(s) have DNSSEC. Ask your mail provider to enable DNSSEC

• MX DNSSEC validation OKrecommended

  DNSSEC not enabled for MX domains

• Mail servers not blacklistedcritical

  1 MX server(s) checked against 16 blacklists - clean ✓

• No critical blacklist listingscritical

  No blacklist listings ✓

• CAA records presentrecommended

  3 CAA record(s) ✓

• CAA policy strictoptional

  CAA limits certificate authorities ✓

• TLSA records (DANE)optional

  No TLSA/DANE records. Add TLSA at _25._tcp.mail for DANE email encryption

• DANE configuration validoptional

  No DANE configured

• No sensitive info in TXTcritical

  No sensitive data leaked ✓

• Verification records reviewedinfo

  2 verification record(s): Google, SpyCloud. Consider if all are still needed

• HTTPS availablecritical

  HTTPS working (status 200) ✓

• Valid certificatecritical

  Certificate chain is valid and trusted ✓

• HTTP redirects to HTTPScritical

  HTTP automatically redirects to HTTPS ✓

• HSTS enabledrecommended

  HSTS enabled (max-age=31536000, includeSubDomains, preload) ✓

• HSTS max-age >= 1 yearoptional

  max-age=31536000 (≥1 year) ✓

• X-Frame-Options headerrecommended

  X-Frame-Options: SAMEORIGIN ✓

• X-Content-Type-Options headerrecommended

  No X-Content-Type-Options header. Add X-Content-Type-Options: nosniff to prevent MIME sniffing

• Content-Security-Policy headerrecommended

  No Content-Security-Policy header. Add CSP to prevent XSS and other injection attacks

• Referrer-Policy headerrecommended

  Referrer-Policy: no-referrer ✓

• security.txt presentoptional

  Contact: https://hackerone.com/slack/

• security.txt validoptional

  security.txt missing required fields. Must have Contact: and Expires: per RFC 9116

• HTTP/3 (QUIC) supportedoptional

  HTTP/3 (QUIC v1) on port 443 Detection methods: QUIC probe: inconclusive (no reply — trigger may be dropped or UDP/443 filtered) Alt-Svc header: h3=":443", h3-29=":443" Cache: 720h (ma=2592000)

• QUIC UDP reachableinfo

  QUIC probe inconclusive (no reply — trigger may be dropped or UDP/443 filtered). Not a negative signal; h3 is judged from Alt-Svc / HTTPS record

• HTTPS DNS record (SVCB)optional

  No HTTPS DNS record (type 65). Add HTTPS record for faster HTTP/3 discovery: slack.com IN HTTPS 1 . alpn="h3,h2"

Add IPv6 support

Request AAAA records from your hosting provider for your website. IPv6 is becoming increasingly important.

Impact: Makes your website accessible to IPv6-only networks