HTTP-Server with preference for “Transfer-Encoding”-Header?

Im currently trying to setup a little showcase and Proof-of-Concept of a HTTP-Request-Smuggling-attack (https://portswigger.net/research/http-desync-attacks-request-smuggling-reborn) with a Content-Length.Transfer-Encoding vulnerabiltiy. In order for that to work I want to build a reverse proxy, such as HAProxy or nginx, and another HTTP-Server in the backend, preferrably in docker, and linking both with docker-compose. All requests that go to…

DNS CNAME lookup fail once in a while

I’ve created the following CNAME record: Name:selector1._domainkey.damvig.com Value: selector1-damvig-com._domainkey.damvig.onmicrosoft.com (It has no A record, but a TXT) The CNAME record is created in the damvig.com zone. When I do a lookup (nslookup -type=CNAME selector1._domainkey.damvig.com 8.8.8.8) I sometimes get: *** dns.google can’t find selector1._domainkey.damvig.com: Non-existent domain TTL is 300. Where is the problem? Is it Google…