The document summarizes several key application layer protocols: Telnet allows remote access to servers by emulating a terminal. FTP is used to transfer files between machines. TFTP is a simplified version of FTP with no security. NFS enables accessing files over a network like local storage. SMTP is the standard for email services. LPD/LPR is for remote printing. X Window provides GUI functionality over networks. SNMP allows monitoring of network devices. DNS translates human-readable names to IP addresses. DHCP automatically assigns IP addresses to devices on a network.