HSRP – hot standby routing protocol. Cisco proprietary. Features a virtual IP and MAC 0000.0C07.ACxx (where xx is the group number) that float amongst members of the group, held by the active HSRP router. For redundancy, not inherently load-balancing.
VRRP – virtual router redundancy protocol, RFC 3768. Very similar to HSRP, uses groups with virtual IP’s and MAC 0000.5E00.01xx where xx is the group number.
GLBP – gateway load balancing protocol. Where an active virtual gateway will hand out 1 of as many as 4 different MAC’s in response to inbound ARP requests, effective load-balancing the traffic across members in the GLBP group.
ARP – address resolution protocol, RFC 826. The protocol used to help a host find the MAC address of an IP address he wishes to send to.
BOOTP – boot protocol, RFC 951. Used to assign IP addresses and other parameters such as name servers, OS boot images and default gateways to requesting clients. Requires that the requesting MAC be configured on the server.
DHCP – dynamic host configuration protocol, RFC 2131. An evolution of bootp, DHCP will assign IP’s to any requesting MAC.
NTP symmetric active mode – where 2 NTP peers mutually synchronize to one another.
NTP server mode – where a Cisco router will serve up the time to querying clients.
NTP client mode – where a Cisco router has been configured with a specific NTP peer to poll for time.
NTP – network time protocol, RFC 1305, version 3. Used to synchronize time among devices.