When many different sources flood the network with traffic until a shutdown occurs due to the overload.

When the attacker copies a trusted IP address to send out packages using this address.

When an outsider inserts themselves into a conversation between two parties and gains access to the data in transmission.

When the attacker uses Trojan horses to infect the browsers.

When the attacker modifies the DNS server to reroute a domain name to a different IP address.