Proper 404 Checking

[sickcodes]

Fastest way I know to fetch head and disconenct, over 80 and 443:

[user@hostname ~]$ curl --head --silent 'https://www.facebook.com/security.txt'
HTTP/2 200 
vary: Accept-Encoding
content-type: text/plain;charset=utf-8
report-to: {"max_age":3600,"endpoints":[{"url":"https:\/\/www.facebook.com\/ajax\/browser_error_reports\/?device_level=unknown"}],"group":"network-errors"}
x-fb-rlafr: 0
document-policy: force-load-at-top
cross-origin-resource-policy: same-origin
nel: {"report_to":"network-errors","max_age":3600,"failure_fraction":0.01}
pragma: no-cache
cache-control: private, no-cache, no-store, must-revalidate
expires: Sat, 01 Jan 2000 00:00:00 GMT
x-content-type-options: nosniff
x-xss-protection: 0
x-frame-options: DENY
strict-transport-security: max-age=15552000; preload
date: Sat, 15 Jan 2022 17:01:40 GMT
priority: u=3,i
alt-svc: h3=":443"; ma=3600, h3-29=":443"; ma=3600