Which of the following types of attacks precedes the installation of a rootkit on a server?

Pharming is a technique used to redirect a user to a fraudulent website, which is unrelated to gaining access or installing malware directly on a server.

A Distributed Denial-of-Service (DDoS) attack aims to overwhelm a server or service with traffic to disrupt its availability, not to install malware.

Rootkits are stealthy malware designed to hide their presence and often other malicious software on a system, requiring deep integration with the operating system kernel or critical system components. To achieve this deep integration and maintain persistence, an attacker typically needs administrative or system-level privileges; therefore, a privilege escalation attack is often performed first to gain the necessary elevated permissions for successful rootkit installation.

A Denial-of-Service (DoS) attack aims to make a service or resource unavailable to legitimate users, which is not a step in installing a rootkit.