Which are two denial-of-service attacks?

The ping of death is a type of attack that involves sending oversized or malformed packets using the ICMP protocol to crash, freeze, or reboot the target system1.

UDP flooding is an attack method that sends a large number of User Datagram Protocol (UDP) packets to random ports on a remote host, causing the host to repeatedly check for the application listening at that port, and (when no application is found) reply with an ICMP Destination Unreachable packet. This process can saturate the network and the resources of the host, leading to denial of service2.

Cloudflare’s explanation of common DoS attacks1.

Wikipedia’s description of denial-of-service attack methods