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cisco a+ certification salary.VRRP is an IP protocol with IP protocol number 112. the VRRP primary router is responsible for generating multicast messages, which it sends to multicast address 224.0.0.18; the primary router generates these messages at an interval of typically 1 second. In the event of a VRRP primary router failure, a VRRP standby router will seamlessly handle traffic sent to the primary router IP address. This process is called object tracking, and it selects the best VRRP router as the primary router based on priority and interface tracking. VRRP supports preemption, so a failed primary router will continue to assume the primary router role after it is repaired.Exam Essentials VRRP object tracking selects the best VRRP router as the primary router based on priority and interface tracking.Note: VRRP configuration is beyond the scope of this book.Gateway Load Balancing ProtocolLike HSRP, Gateway Load Balancing Protocol ( GLBP) is a Cisco-specific protocol. One limitation of HSRP and VRRP is that only one router is the active router, responsible for forwarding traffic, while all other routers are idle. This is inefficient because one or more routing devices do not handle any traffic and cannot utilize the bandwidth of the links to which they are connected.To avoid this problem, Cisco designed the GLBPo GLBP supports dynamically assigning a set of virtual addresses to endpoints, allowing up to four routing devices to participate in traffic forwarding. In addition, if a GLBP routing device fails, it will be able to automatically detect such failure, and another GLBP routing device will take over the packet forwarding for that routing device.The following are some of the advantages of GLBP.. Like HSRP, GLBP supports authentication between GLBP routing devices using both plaintext and MD5 passwords. . GLBP supports up to 1024 virtual routers on a routing device.. GLBP can use up to four routing devices in a subnet or VLAN to balance the load.Exam Essentials Be sure to familiarize yourself with the benefits of GLBP.