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Download 1. Application layer, Transport layer, Internet layer, Link layer 2
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1. Application layer, Transport layer, Internet layer, Link layer 2. Application layer: DHCP, HTTP, BGP, SMTP, POP Transport layer: TCP, UDP, Internet layer: IP, ICMP, IPSec Link layer: ARP, PPP 3. Switches operate at Layer 2 of the OSI model and switch frames based on the MAC addresses. Switches only forward frames within the same broadcast domain. Routers operate at the Layer 3 of the OSI model and route packets based on the network IDs (IP addresses). Routers route packets to different network domains. If a destination is not known to a switch, it broadcasts the frame, whereas a router may drop a packet if the destination is not known (or send on a default route, depending uptown scenario/configuration). 4. A packet is a protocol delivery unit (PDU) that is exchanged between hosts at Layer 3 of the OSI model. In TCP/IP, IP packets consist of a header and payload and are routed based on the source/destination IP addresses contained in the header, amongst other things. A frame is a PDU at the Layer 2 of the OSI model. A packet is encapsulated in one of more frames (depending on the size of the packet and maximum transmission unit of the frame) e.g. in Ethernet frames. 5. Connection-oriented protocols require that a logical connection be established between two device before transferring data. Connectionless protocols do not establish a connection between devices before exchanging data, the sender starts sending as soon as it wants to, without considering if the receiver is able to receive data, can accommodate a certain data rate, etc. TCP is a connection-oriented protocol, whereas UDP Is a connectionless protocol. 6. Unicast: When information is sent from one point to another e.g. a packet is sent from a single source to a specified destination. Multicast: Communication in which information is sent from one or more points to a set of other points e.g. as in IP multicast using UDP. Broadcast: Communication in which a price of information is sent from one point to all other points, e.g. in a LAN 7. RIP and BGP are routing protocols, where as Store-and-Forward is the one of the methods used in switching e.g. Switches can store an incoming frame and then send it to its destination later. 8. Sliding window protocols are used to enforce reliable in-order delivery of packets. Each packet is assigned a unique consecutive sequence number and the receiver uses the numbers to place received packets in the correct order. Duplicate packets are discarded and any missed packets are identified using this sequencing. To limit the sequence of numbers from growing unreasonably large, limits are placed on the number of packets than can be transmitted or received at any given time before requiring an acknowledgement. Thus unlimited number of messages can be exchanged using fixed-size sequence numbers. 9. Maximum Transmission Unit, the size of the largest protocol data unit at a layer in the network stack. Ethernet MTU is 1500 octets 10. Distributed Denial of Service Attack, in which the intention is to make a network host - and hence any services it provides - unavailable to its users. 11. ARP 12. DNS 13. traceroute (tracert on Windows) 14. HTTP 80 FTP 21 SSH 22 TELNET 23 SMTP 25 15. By using the 'ping' command