ISDN BRI Two 64Kbps B channels and one 16Kbps D channel
ISDN PRI Twenty-three 64Kbps B channels (US) and one 16Kbps D channel
TCP A reliable, slow, and connection-oriented protocol that ensures that packets are delivered to the destination computer
UDP A fast, best-effort, non-connection-oriented protocol
Distance-vector protocols: RIP
Link-state protocols: OSPF
Asynchronous communication Two devices are not synchronized in any way.
Synchronous communication Two devices are synchronized and usually controlled by a clocking mechanism.
Demilitarized zone (DMZ) A network segment that is located between the protected and the unprotected networks.
Bastion host A device that has been hardened and is to be deployed in the DMZ.
Packet filtering Considered a first level of defense. Access is based on rules.
Stateful packet filtering Method of control that keeps a state table to keep track of activity and control access.
Proxy Stands between the trusted and untrusted network.