<p> Cheat Sheet CCNA </p><p>Class A: 255.0.0.0 also denoted as /8 (CIDR) Class B: 255.255.0.0 also denoted as /16 (CIDR) Class C: 255.255.255.0 also denoted as /24 (CIDR) Bits 1 1 1 1 1 1 1 27 26 25 24 23 22 21 Increment 128 64 32 16 8 4 2</p><p>Subnet mask 128 192 224 240 248 252 254 Usable Host 126 62 30 14 6 2 - A/8 /9 /10 /11 /12 /13 /14 /15 B/16 /17 /18 /19 /20 /21 /22 /23 C/24 /25 /26 /27 /28 /29 /30 /31</p><p>Routing RIP v1 RIPv2 OSPF EIGRP Protocols Distance vector Distance vector Link-state Advance Distance vector Slow convergence Slow Fast Faster convergence Hop count Hop count Bandwidth Bandwidth, cost, reliability, delay Config. Router rip Router rip Router ospf 1 Router EIGRP 2 Statements Network X.X.X.X Ver 2 Net X.X.X.X wildcard mask Area 0 Net X.X.X.X Network X.X.X.X Network X.X.X.X Net Y.Y.Y.Y wildcard mask Area 0 Net Y.Y.Y.Y no auto-summary no auto- No auto-summary summary Required Process ID  AS number must be the same Wild card mask must be correct  no auto-summary Area must be added Watch for Hello and dead timer Autonomous system number (AS) Process ID 1-65535 Successor (in the routing table) Feasible successor( backup route in the topology table)</p><p>Wildcard mask 255.255.255.255 Calculation - 255. 255. 255. 0 (actual Subnet mask) 0 .0. 0. 255</p><p>Router ID Router ID has 3 criteria for assignment 1. Could be manually assigned 2. Use Loopback address i. If more than one loopback exit, loopback with highest IP address will be used 3. The physical interface with the highest IP address will be used. Cheat Sheet CCNA Spanning Tree Protocol 1.Switch Priority determines who the root bridge is 2.MAC address used if priorities are the same 3.BPDU still go through alternate ports 4.All ports on root bridge are Designated ports (forwarding packets) 5.Root ports connect other switches to root bridge (also Designated ports) 6.Alternate ports are in “Block Mode”</p><p>Spanning-tree port fast will convert STP to RSTP (port will change from “blocked” directly to “forwarding” mode</p><p>Access Control List (ACL)  Standard and Extended  Standard(1-99) ES vs SD  Extended (100-199) Synthax Access-list 100 permit tcp host X.X.X.X host Y.Y.Y.Y eq 80 Access-list 100 deny tcp any host Y.Y.Y.Y eq 80 Access-list 100 permit ip any any (access-list <number> <action> <protocol> <Source><Destination></p><p>To apply: Navigate to the interface of choice and do</p><p>IP access-group 100 in End Copy run start. (very important step)</p><p>Troubleshootin Ping g tips Traceroute Show ip protocols Show ip interface brief Show ip route</p>