Data Communication Reviewer
Reviewer DataCom: Chapter 1-5 Chapter 1: Intranet- Restricted accumulation on a aggregation and alone allows centralized agent access. Extranet- Type of arrangement that allows alfresco vendors appropriate admission to bound advice in a company. Protocols- Rules of communication. * An articular sender and receiver * An agreed-upon adjustment of communicating * Accepted accent and grammar * Confirmation or accepting requirements Elements of a Network: * Rules or agreements: protocols or how the bulletin is semt, directed, accustomed and interpreted. * Massages: units of advice that campaign Medium: agency of abutting these devices, can carriage the messages
* Devices: accessories on the arrangement barter letters Messages- a all-encompassing appellation that encompasses forms of advice enabled by the Internet. Devices- several accessories assignment to see that the bulletin is appropriately directed to the antecedent to the destination device. Icons- symbols that graphically presents arrangement accessories and media. * Desktop Computer * Laptop * Server – a computer committed to accouterment app casework * IP Phone – a agenda phone
* LAN media * Wireless media LAN about-face – best accepted accessory for interconnect LANs * Firewall – provides aegis to networks * Router – helps absolute letters amid networks * Wireless router * Cloud – abridge a accumulation of networking accessories * WAN media IP (Internet Protocal) & TCP (Transmission Ascendancy Protocol) – best accepted protocols * WWW – HTTP * E-mail – SMTP * Instant messae – XMPP * IP telephony – SIP Convergence – advancing calm of technologies assimilate a agenda platform. It occurs aback computer communications all use the aforementioned rules to carriage their messages. Arrangement Architecture – the conceptual affairs on which a concrete arrangement is built. Fault tolerance- needs to action alike if some apparatus abort * Scalability- network’s adeptness to abound & acknowledge to approaching changes * Quality of service- achievement akin of services. Prioritize cartage and its characteristics to administer data. * and Aegis Packets-single bulletin is burst into baby blocks of data. Bandwidth- admeasurement of the data-carrying accommodation of the network. Chapter 2: Elements of communication: * Bulletin source, or sender * Destination, or receiver *
Channel- media that provides alleyway Network- refers to abstracts networks accustomed massages. Segmentation- all letters are burst into abate pieces Multiplexing- occurs aback segments of two letters can drag into anniversary alternative and allotment the medium. * Increased ability of arrangement advice End device- a allotment of accessories that is either the antecedent or the destination of a bulletin on a network. Host- an end accessory that sends or receives messages. Clients- alternative hosts that set up to abundance and allotment advice by the host servers *The host abode is a altered concrete abode acclimated by hosts central a LAN. Intermediary device- connects the alone host to the arrangement and affix assorted alone arrangement to anatomy an internetwork. Arrangement admission devices
* Internetwork accessories * Advice severs * Modems * Aegis accessories Arrangement media: Copper, Fiber-optic cable, Wireless Encoding- refers to the way abstracts is adapted to patterns of electrical, light, or electromagnetic energy. LAN- a accumulation of end accessories and users beneath the ascendancy of a accepted administrator. WAN- a arrangement that is acclimated to affix LANs that are geographically far apart. Internetwork- is a accumulating of two or added LANs affiliated by WANs. Proprietary – A limited-use agreement endemic by a company. Arrangement Representations: Arrangement interface agenda (NIC)- provides the concrete affiliation to the arrangement at the PC or alternative host device. * Concrete port- is a adapter or aperture on a networking accessory breadth the media is affiliated to a host.
* Interface- refers to how the accessory can acquiesce 2 altered networks to communicate. The organizations that assimilate networking protocols are: * IEEE – Institute of Electrical and Electronics Engineers * IETF – Internet Engineering Task Force Interaction of Protocols: * Hypertext Alteration Agreement (HTTP) – accepted agreement that governs the way that a web server and a web applicant interact. Carriage agreement – Manual Ascendancy Agreement (TCP) is the carriage agreement that manages the alone conversations amid web servers and web clients. * Internetwork agreement * Arrangement admission protocols – describes 2 primary functions: Data-Link Management & the concrete manual of abstracts on the media. Layered Models – call the circuitous action of arrangement communication. Open Systems Interconnection (OSI) – is the best broadly accepted internetwork advertence model.
Provides an abstruse description of the arrangement advice process. Developed by International Organization for Standardization (ISO). Application, Representation, Session, Transport, Network, Abstracts Link, Concrete TCP/IP Archetypal – defines the 4 advice functions that protocols perform. * Application, Transport, Internet, Arrangement Admission Encapsulation- Action of abacus ascendancy advice as it passes through the layered archetypal Decapsulation- action of removing added advice Agreement Abstracts Unit (PDU) – all-encompassing appellation for abstracts at anniversary level. Chapter 3: Presentation Band has 3 primary functions: * Coding and about-face of appliance band abstracts * Compression of the abstracts * Encryption of the abstracts TCP/IP protocols: Area Name System (DNS) - acclimated to boldness internet names to IP address. * HTTP – acclimated to alteration files that accomplish up the web pages of the WWW. * Simple Mail Alteration Agreement (SMTP) – acclimated for the alteration of mail letters and attachments. * Telnet – a terminal appetite agreement acclimated to accommodate alien admission to servers and networking devices. * Book Alteration Agreement (FTP) – acclimated for alternate book alteration amid systems. Action – anniversary active affairs loaded on a device. Client/server archetypal Deamon – are describes as “listening” for a appeal from a client. Appliance band casework and protocols
Peer-to-peer networking and applications * 2 or added computers are affiliated through a arrangement and can allotment assets such as printers and files after accepting a committed server. nslookup – a account that allows the user to manually concern the name servers to boldness a accustomed host name. ipconfig/displaydns – displays all the buried DNS entries 3 accepted bulletin types are: * GET- is a applicant appeal for data. * POST and PUT- are acclimated to accelerate letters to that upload abstracts to the web browser. E-Mail Server Processes: * Mail Alteration Agent (MTA) – action acclimated to advanced e-mail. * Mail Commitment Agent (MDA)
Server Bulletin Block (SMB) – a client/server file-sharing protocol. Chapter 4: Carriage Band – provides cellophane alteration of abstracts amid end users, accouterment reliable abstracts alteration casework to the high layers. It enables applications on accessories to communicate. * Tracking the alone communications * Segmenting abstracts and managing anniversary allotment * Reassembling the segments * Identifying the altered applications * Performing breeze ascendancy amid end users * Enabling absurdity accretion * Initiating a affair Breeze Ascendancy – can anticipate the accident of segments on the arrangement and abstain the charge for retransmission.
Used to abstain absorber overflows. Two best accepted carriage layer: TCP (Transmission Ascendancy Protocol) – incurs added aerial to accretion functions. * Web browsers, E-mail, Book transfers UDP (User Datagram Protocol) – accommodate the basal functions for calmly carrying the abstracts pieces. Has the advantage of accouterment low-overhead abstracts delivery. * DNS, Video streaming, Voice over IP (VoIP) 3 basal operations of reliability: * Tracking transmitted abstracts * Acknowledging accustomed abstracts * Retransmitting any bearding abstracts Socket – refers alone to the altered aggregate of IP abode and anchorage number.
Internet Assigned Numbers Authority (IANA) – assigns anchorage number. Altered types of ports: * Well-known ports (0 to 1023) – aloof for casework and applications. * Registered ports (1024 to 49151) – are assigned to user processes or applications. * Dynamic or clandestine ports (49152 to 65535) – additionally accepted as brief ports, are usually assigned dynamically to applicant applications. netstat – a command that is an important arrangement account that you can use to verify TCP connections. It lists the agreement in use, the bounded abode and anchorage number… Datagram – is a UDP articulation (piece).
Flags – are six 1-bit fields accommodate ascendancy advice acclimated to administer the TCP processes: * URG: Urgent arrow acreage cogent * ACK: Accepting acreage cogent * PSH: Push action * RST: Reset the affiliation * SYN: Synchronize arrangement numbers * FIN: No added abstracts from sender *flags accept fields that the alone bulk is 1 bit and, therefore, has alone two values: 1 or 0. 3 way handshake: Step 1 – SYN, Step 2 – SYN and ACK, Step 3 – ACK. Expectational accepting – occurs aback TCP uses the accepting cardinal in segments beatific aback to the antecedent to announce the abutting byte in this affair that the receiver expects to receive.
Window admeasurement – is the bulk of abstracts that a antecedent can abode afore an accepting charge be received. Chapter 5: OSI Band 3 – provides casework to barter the alone pieces of abstracts over the arrangement amid articular end devices. The arrangement band describes four tasks to be performed: * Acclamation packets with an IP abode * Encapsulation – is the action of abacus that information. * Acquisition – is the action router accomplish aback accepting packets… * Decapsulation – is the action of removing encapsulation abstracts at altered layers. Antecedent IP abode – is the IP abode of the sending host
Destination IP abode – is the IP abode of the accepting host. IP attack – contains the abode advice and some alternative $.25 that analyze the PDU as a arrangement band PDU. Packet – is referred aback an OSI band 4 PDU has been encapsulated at the arrangement layer. Hop – is anniversary avenue that a packet takes to ability the abutting device. Accepted arrangement protocol: * IPv4 – best broadly acclimated arrangement protocol. * IPv6 – currently in use in some area. * Novell IPX – a broadly accepted internetworking agreement in the 1980s and 19990s. * AppleTalk – Apple Computer’s accordance networking protocol. Connectionless Arrangement Service (CLNS) – a agreement acclimated in telecommunication network. IPv4 basal characteristics: * Connectionless * Best accomplishment (unreliable) * Media absolute *Some networks accept media restrictions and charge accomplish a Maximum Manual Unit (MTU). Fragmentation – is the action aback the arrangement band builds the packets according to specification. Key fields: * IP antecedent acclamation * IP destination acclamation * Time to Live (TTL) * Type of Service (ToS) * Agreement * Flag and Fragment Offset Alternative Key Fields: * Version * Internet Attack Length (IHL) * Packet Length * Identification Attack Checksum * Options * Padding *Because advertisement do not biking above the arrangement boundary, the arrangement is accepted as a advertisement domain. Gateway router – is the router a arrangement uses to accelerate and accept letters above the network. Hierarchical acclamation – is apprehend from the best accepted advice to the best specific. Subnetting – the action aback a ample arrangement needs to be disconnected into abate subnets, added arrangement codes can be created application some of the $.25 appointed for the host. *The absence avenue is acclimated aback the destination arrangement is not represented by any alternative avenue in the acquisition table.
Next hop – is the abode of the accessory that will action the packet next. *The avenue advice can be manually configured on the router, creating what is accepted as a changeless route. Dynamic acquisition – aback routers apprentice about routes automatically from alternative routers in the aforementioned internetwork. Acquisition Protocols – are the set of rules by which routers dynamically allotment their acquisition information. * Acquisition Advice Agreement (RIP) * Enhanced Interior Gateway Agreement (EIGRP) * Open Shortest Path First (OSPF) 3 key factors to accede aback alignment hosts into a accepted network: * Purpose * Ownership * Geographic location
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