Full HTTP probe
Run /check/t.co to see live status, response time, and 24h history.
DNS records
t.co DNS records
t.co
7 record types
RESOLVED
1s ago
What this means
The hostname resolves and is reachable at the DNS layer. If browsers can't reach it, the issue is downstream of DNS — TLS, HTTP routing, or a firewall block. Try /check/t.co next.
Records
A
172.66.0.227
AAAAno records
CNAMEno records
MXno records
NS
a.u06.twtrdns.netb.r06.twtrdns.netb.u06.twtrdns.netc.r06.twtrdns.netc.u06.twtrdns.netd.r06.twtrdns.netd.u06.twtrdns.neta.r06.twtrdns.net
TXT
1nfb08f5jkpy0flhn6lwml2vk7x34hrd1z8q6j6wymwb6bh0t3q28tp7vsbgnh6d48qgbs8f2v055y997kpf4cx2302fzfs2v=spf1 -all
SOA
nsname a.u06.twtrdns.net
hostmaster noc.twitter.com
serial 2023121101 · refresh 3600s · retry 600s · expire 604800s · minttl 3600s
Operational warnings
- No AAAA records — site is IPv4-only. Modern networks expect both.
What to try next
TLS certificate
Inspect the live cert at /ssl/t.co.
Compare resolvers
Run dig +short A t.co @1.1.1.1 and @8.8.8.8 — if they disagree, propagation is still in flight.
Methodology
- Probe
- We resolve A, AAAA, CNAME, MX, NS, TXT, and SOA records in parallel via Node's built-in dns.promises against the system resolver. Every query has a 5-second timeout; non-existent record types are reported as no records rather than errors.
- Counts as DOWN
- All address-resolution attempts fail. The most informative form is NXDOMAIN (the authoritative server explicitly says "no such name"); other forms are server errors or timeouts.
- Counts as DEGRADED
- Reserved for partial responses — some record types resolved, others timed out. Usually a flaky upstream or rate-limited authoritative server.
- Detail
- We surface the records as the resolver returned them, plus operational warnings: missing AAAA (IPv4-only), missing MX (cannot receive mail at the apex), missing SPF in TXT (outbound mail likely flagged as unauthenticated). We do not enumerate zone files, attempt zone transfers (AXFR), or run DNSSEC validation.
- Cadence
- Every 5 minutes, in parallel across 4 monitoring regions (US East Virginia, US West Oregon, Europe London, Asia Singapore).
- Rate-limited targets
- If a host returns 429 or consistently drops connections from our IPs, we cap retries at 3 and report the last observed status — we do not flood the target to confirm the outage.
- Data source
- Direct probes from our monitoring infrastructure. We do not aggregate crowd reports, Twitter mentions, or DownDetector signals — every result on this page is a live network request.