Brodcast domain--logical division in which every node can reach each other by brodcast at the datalink layercollision domain-->A collision domain is a physical network segment where data packets can collide with one another when being sent on a shared medium.Open system interconnection(OSI Model)--seven layers-->Application, presentation, session, transport, Network ,datalink, physicalapplication provides user interfacepresentation handles encryption,compression, translation services. session-->keeps different applications data separate(Dialog control)Transport-->end to end connection.Network---logical addressingDatalink--FramingCIDR(classless interdomain routing)===================================VLSM(Variable Length subnet Mask)=================================Troubleshooting:================ping 127.0.0.1 --ping failure-->TCP/IP needs to be reinstalledping local-ip-address -->ping failure-->NIC is not functiongping local gateway -->ping failure--->local problem anywhere between router and the PC.sh ip arp-->arp mappings in cisco routerCisco IOS(internetwork operating system) is the kernel of the operating system.circuit switching -->The circuit functions as if the nodes were physically connected as with an electrical circuit.Circuit switching is a telecommunications technology by which two network nodes establish a dedicated communications channel (circuit) before the nodes may communicatePacket switching is the process of segmenting a message/data to be transmitted into several smaller packets. Each packet is labeled with its destination and a sequence number (for ordering related packets), precluding the need for a dedicated path to help the packet find its way to its destination. Each is dispatched and many may go via different routes.ISDN and ATM?Difference between Gateway and ROuter?ROUTERnetwork device that forwards packets from one network to another. Based on internal routing tables, routers read each incoming packet and decide how to forward it.Routers work at the network layer (layer 3) of the protocolGATEWAYdevice that converts one protocol or format to another. A network gateway converts packets from one protocol to another.the gateway functions as an entry/exit point to the network.An earlier name for router.GATEWAY work at the Transport layer or session layer (layer 4) of the protocolwat is subnetting?Used in IP Networks to break up larger networks into smaller subnetworks. It is used to reduce network traffic, Optimized network performance, and simplify management i.e. to identify and isolate network problems.difference between RARP and ARP?ARP is used to determine the physical address(MAC Address) of the device only when its ip address is known. ARP is also used to translate the IP address to Ethernet MAC address. Each device has a physical address imprinted on the Network Interface Card(NIC).ARP used to associate an IP address with the phycial address.RARP is used to determine the IP address of the host only when the physical address (MAC Address) is known. It's useful when the computer is connected to the network for the first time.what is MTU?maximum transmission unit (MTU) of a communications protocol of a layer is the size (in bytes) of the largest protocol data unit that the layer can pass onwards.Integrated services router(ISR)?2800 series of routers is called ISR since service like security has been built on it.Ibt has SDM (security device Manager) for configuration of router via web console.Startting process of router?bootstrap-->stored in ROM boot the router and then load the IOS.POST(power on self test)--stored in rom does the testing of hardware and determines which interfaces are present. CDP(cisco discovery protocol)?help administrators collect information about both locally attached and remote devices.sh cdp neighbours detail--give information about the neighbouring devicesRouting Protocols types?Distance vector--The distance-vector protocols find the best path to a remote network by judging distanceLInk state--In link-state protocols, also called shortest-path-first protocols, the routers each create three separate tables. One of these tables keeps track of directly attached neighbors, one determines the topology of the entire internetwork, and one is used as the routing table.