HTTP 1.1 uses TCP and UDP for transport (UDP is only used for small entities, e.g icons).

In HTTP 1.0 you can only host one website / IP.

The Host Header was introduced in HTTP 1.1 to allow hosting multiple HTTP sites on a single IP address.

HTTP DIGEST is a secure way to exchange authentication credentials.

HTTP Sessions handling relies on information found in the TCP session.

The DS record contains the hash of the parent zone KSK.

DNS uses both, UDP and TCP, as transport protocols.

A server that (authoritatively) hosts a signed zone is directly asked for a record. If the signature of this record is valid, the server will respond with the "authenticated data" (AD) flag set.

For working DNSSEC, the whole chain up to the root must be signed.