CCNA Study

 Swithch> show ? ----Lists all commands. If you enter show? It will shows just "show". If yo type " enable " it will change to Switch# from Swich> Switch# debug ? Switch#c onfigre ? Switch#configure terminal ? Switch#conf t Swtich(config)#hostname HAL HAL(config)#hostname SW1 SW1(config)#^Z SW1#show config SW1#wr SW1#conf t SW1(config)#no service timestamps SW1(config)#line console 0 SW1(config-line)#logging ? SW1(config-line)#exec-timeout 0? SW1(config-line)#exec-timeout 0 0 --->This negates time out. We will not be kicked out ever.  VLAN: It helps us group hosts by department, security clearances, locations, etc. It also prevents broadcast storms by limiting the scope of broadcasting.  HOST_1#pintg10.1.1.2 --->only sends 5 HOST_1#ping Protocol [ip]: Target IP address: 10.1.1.2 Repeat count [5]:10 If you enter wrong IP with 1 million ping, you need to type ctrl shift 6 to get out.  SW1#show vlan SW1#show cdp neighbor SW1#show cdp neigh detail SW1(config...

 1. Collision Domains and CSMA/CD  What is a collision domain? When shared media is connected each other using Ethernet and multiple devices are sending data simultaneously Collins happen because sending and receiving is not supported at the same time which cause the loss of data nd time associated with collisions. Therefore, Carrier Sense Multiple Access with Collision Detection (CSMA/CD) was developed. Before sending data, a host will check to see if any other host is already sending data.  2. Broadcasting When a Hub receives a broadcast it sends it to every single port on the Hub. Bridge will resolve the issue with collision domain but it will not segment the broadcasting. However, switch can segment the broadcast.  3. MAC Address table  Command: show mac address -table or show mac address dynamic. If you need help for the command, type show mac address -table  ? Mac address table is used to help us make a decision on what to do with the incoming frames....

<The OSI Model> Layer 7: Application -End users interact with the network; Data integrity, privacy, and the presence of absence or absence of error recovery natures. (e.g. Gmail, Facebook, Twitter) Layer 6: Presentation - Data presentation, data encryption (e.g. SSL/TLS) Layer 5: Session - The manager of data transfer process; Session creation, maintenance, and teardown of the communications (e.g. Tunneling protocols) Layer 4: Transport -The "post office: layer (e.g. TCP segment, UDP datagram) Layer 3: Network - Routing layer (IP address, router, packet) Layer 2: Data Link - Switching layer (Frame, MAC address, EUI-48, EUI-64, Switch) Layer 1: Physical -Network cabling  When I send a photo to my friend A, the data is in an original format until it reaches to layer 4 where data gets segmented into segments and then at Layer 3 it becomes packets and at layer 2 it becomes frames and then finally it becomes bits 1s and 0s.  <The TCP/IP Model> Application: FTP, BOOTP, T...