ccna certification online exam

ccna certification online exam.>[TechBook EssentialsIn the actual application environment, when the router's G0/0 interface starts up, it will actively send GratuitousARP (free ARP), and the computers in the same network segment will update their ARP cache table after receiving the packet; when the computer NIC starts up, it will actively send ARP requests periodically in order to get the MAC address of the gateway, so the process of above is actually The process of above is actually done automatically and does not require the user to send packets to trigger it.After PC1 receives the ARP reply packet from router R1, it can perform Ethernet encapsulation with the following address information:Source MAC address Destination MAC address Type Source IP address Destination IP address Protocol0060.3E37.BC77 0090.0c42.7b01 0x0800 172.16.1.100 172.16.2.100 0x01Computer PC1 sends the packet to the default gateway, router Rl,R1 receives the Ethernet frame from interface G0/0, decapsulates the packet (removes the Layer 2 frame header and frame tail), and then router R1 searches the routing table for a matching route entry using the packet's destination IP address 172.162100. After finding a matching destination network address in the routing table, the outgoing interface is determined to be S0/0/0,.59 . Cisco Networking Lab CCNA Lab Guide (Release 2) R1 reencapsulates (layer 2 rewrites) the packet into a PPP frame and forwards the packet to router R2,with the following address information.PPP address Type Source IP address Destination 1P address ProtocolOxFF 0x0021 172.16.1.100 172.16.2.100 0x01After router R2 receives the packet from R1, it decapsulates the packet (removes the Layer 2 frame header and frame tail), and router R2 searches the routing table for a matching route entry using the destination IP address of the packet, 172.16.2.100. After finding the destination network address in the routing table, you find that the destination host location is the same as your own directly connected G0/0 interface network. At this time, if there is no ARP cache corresponding to 172.16.2.100 in Router R2's ARP table, you send an ARP request in order to obtain the MAC address information of Serverl's NIC, which is as follows.