Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts, first/last seen and live DNS status.

68 hosts · 382 ms

HostCertsFirst seenLast seenDNS
nationalgridus.com 11 2026-05-29 2026-09-25 ok
*.nationalgridus.com 26 2026-04-13 2026-04-15 —
www1.nationalgridus.com 6 2026-05-08 2026-09-04 ok
www2.nationalgridus.com 10 2026-04-14 2026-08-10 ok
live-shared-content3.nationalgridus.com 11 2026-05-23 2026-09-19 ok
test-shared-content3.nationalgridus.com 6 2026-05-02 2026-08-28 ok
dev-shared-content3.nationalgridus.com 12 2026-05-02 2026-08-28 ok
live-content3.nationalgridus.com 10 2026-04-22 2026-08-18 ok
test-content3.nationalgridus.com 10 2026-04-11 2026-10-05 ok
dev-content3.nationalgridus.com 9 2026-04-12 2026-10-06 ok
test-content4.nationalgridus.com 13 2026-04-10 2026-10-05 ok
dev-content4.nationalgridus.com 12 2026-04-15 2026-08-11 ok
itdev-content4.nationalgridus.com 12 2026-04-13 2026-08-09 ok
live-shared-content5.nationalgridus.com 12 2026-05-24 2026-09-20 ok
test-shared-content5.nationalgridus.com 8 2026-05-03 2026-08-30 ok
dev-shared-content5.nationalgridus.com 10 2026-05-02 2026-08-29 ok
live-content5.nationalgridus.com 8 2026-04-22 2026-08-18 ok
test-content5.nationalgridus.com 12 2026-06-07 2026-10-03 ok
dev-content5.nationalgridus.com 8 2026-04-16 2026-08-13 ok
live-content6.nationalgridus.com 12 2026-04-27 2026-08-23 ok
test-content6.nationalgridus.com 8 2026-04-27 2026-08-23 ok
dev-content6.nationalgridus.com 12 2026-04-27 2026-08-23 ok
www9.nationalgridus.com 10 2026-05-25 2026-09-21 ok
outagemap.ma.nationalgridus.com 12 2026-05-04 2026-08-31 ok
ebb-qa.nationalgridus.com 8 2026-05-07 2026-09-02 ok
aspen-qa.nationalgridus.com 12 2026-05-21 2026-09-17 ok
acis-qa.nationalgridus.com 10 2026-05-21 2026-09-17 ok
gtis-qa.nationalgridus.com 21 2026-04-30 2026-09-16 ok
ebb.nationalgridus.com 21 2026-03-17 2026-09-11 ok
online.nationalgridus.com 13 2026-05-30 2026-09-25 ok
uat-online.nationalgridus.com 8 2026-04-12 2026-10-06 ok
test-online.nationalgridus.com 13 2026-04-10 2026-10-04 ok
cite.nationalgridus.com 5 2026-05-20 2026-09-17 ok
mtls-b2capi.nationalgridus.com 1 2026-03-17 2026-03-17 nxdomain
uat-mtls-b2capi.nationalgridus.com 1 2026-03-02 2026-03-02 nxdomain
test-mtls-b2capi.nationalgridus.com 1 2026-03-16 2026-03-16 nxdomain
dev-mtls-b2capi.nationalgridus.com 1 2026-03-16 2026-03-16 nxdomain
tsari.nationalgridus.com 9 2026-05-19 2026-09-14 ok
clearpassuk.nationalgridus.com 1 2025-12-03 2025-12-03 ok
lab-clearpassuk.nationalgridus.com 1 2025-11-07 2025-11-07 nxdomain
aspen.nationalgridus.com 7 2026-05-21 2026-09-17 ok
login.nationalgridus.com 11 2026-04-15 2026-09-29 ok
qa-login.nationalgridus.com 2 2026-03-20 2026-07-30 ok
uat-login.nationalgridus.com 16 2026-04-14 2026-09-28 ok
dev-login.nationalgridus.com 2 2026-03-17 2026-07-27 ok
networklogin.nationalgridus.com 1 2025-11-17 2025-11-17 nxdomain
ftp.nationalgridus.com 1 2026-02-04 2026-02-04 ok
unyinstantrebates.nationalgridus.com 5 2026-05-10 2026-09-09 ok
gasrates.nationalgridus.com 12 2026-04-23 2026-08-19 ok
acis.nationalgridus.com 13 2026-04-07 2026-09-06 ok
gtis.nationalgridus.com 13 2026-05-16 2026-09-18 ok
cloud.emails.nationalgridus.com 1 2025-11-05 2025-11-05 ok
image.emails.nationalgridus.com 4 2026-01-03 2026-09-06 ok
click.emails.nationalgridus.com 1 2025-11-05 2025-11-05 ok
view.emails.nationalgridus.com 1 2025-11-06 2025-11-06 ok
clearpass.nationalgridus.com 1 2025-11-20 2025-11-20 ok
uat-us.nationalgridus.com 12 2026-04-12 2026-08-09 ok
test-us.nationalgridus.com 10 2026-04-15 2026-08-11 ok
news.nationalgridus.com 5 2026-04-30 2026-08-29 ok
dev-news.nationalgridus.com 4 2026-04-14 2026-08-14 ok
content.nationalgridus.com 3 2025-10-17 2026-09-25 ok
test-content.nationalgridus.com 11 2026-04-11 2026-10-05 ok
dev-content.nationalgridus.com 8 2026-04-13 2026-08-10 ok
request.nationalgridus.com 17 2026-05-09 2026-09-04 ok
optout.nationalgridus.com 8 2026-04-16 2026-08-12 ok
online-dev.nationalgridus.com 8 2026-05-06 2026-09-01 ok
www.nationalgridus.com 10 2026-05-18 2026-09-14 ok
outagemap.ny.nationalgridus.com 10 2026-05-04 2026-08-30 ok

Programmatic access, with DNS A records: API GET /v1/hosts/nationalgridus.com (API key for paging).

Shown here: hostnames with a certificate that is valid now or expired within the last 90 days. The full history since 2013 — hostnames whose last certificate expired earlier — is a Pro plan method: GET /v1/hosts-history/nationalgridus.com.