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Process of Finding Hosts on the Same Network Segment- ARP Assume that host A and host B are on the same LAN. Host A broadcasts an ARP request onto the LAN looking for host B. Because it is a broadcast message all devices on the LAN, including host B, process the request. However, host B is the only device to respond and it does so with its MAC address. Host A receives host B reply and stores the MAC address in local memory. This is often called an "ARP cache". The next time host A needs to communicate with host B it recalls host B stored MAC address. Process of Finding Hosts on the Different Network Segment- ARP + Router Let's look at how host Y communicates with host X on a different LAN, which it can access via router A. As before host Y broadcasts its ARP request. Router A, along with all the other devices on the LAN, processes the request. It knows that host X will not see the request because it is on another LAN, and that any packets destined for host X will hav...

The technical definition of LAN and WAN does not depend upon the Graphical Distance. So, we can define LAN and WAN as follow: The technology which we use for the communication on the Physical Layer and Data Link Layer decides whether we are doing LAN Communication or WAN Communication. LAN (Local Area Network) If we are using Ethernet Technology which run on Physical and Data Link Layer for the communication between two computers even they are l00 kilometers far from each other then it is called LAN (Local Area Networks). WAN (Wide Area Network) If we are using V,35, or EIA/TIA-232 which run on Physical Layer and PPP or HDCL Protocol on Data Link Layer for the communication between two Computers even they are placed nearer to each other it will be WAN (Wide Area Network).

1-TCP converts upper layer data in to segments and the segments are numbered and sequenced so that the destination TCP can place them in the same order, and can easily detect a missing segment. But in UDP data is broken in to segments and the segments are numbered but not sequenced. 2-TCP is connection oriented because it creates a virtual circuit between the source and destination before sending data. But UDP does not create any virtual circuit before sending data. 3-TCP uses acknowledgement to resent missing segments, but there is no acknowledgement in UDP. 4-So we can say TCP provide reliable communication but UDP provides unreliable communication. 5-Since TCP is creating virtual circuits, TCP is costly in terms of bandwidth. But UDP has low overhead

Hubs work at the Physical layer. A hub is a totally dumb device. If it gets a data signal, it just forwards the signal to all devices. It cannot do any kind of filtering or addressing. Performance is not so good because a hub can't establish a direct connection from one computer to another. If a switch gets a data packet, it will try and find the destination device, and then send it to that device only, i.e. it establishes a point-to-point connection between the sending and receiving devices. But the devices must be on the same subnet. A switch won’t send data packet to computers on different subnets. A switch breaks up collision domains but it does not break up broadcast domains unless we use VLANs. Like Switches, Bridges operate at the Data Link layer and filter packets based on the MAC address. Generally bridges are used to extend the distance capabilities of the network while minimizing overall traffic, and switches are used mainly fo...