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CCNA Vocabulary 1

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Below is list of terms you need to know for the CCNA exam.

Access Link The serial link (physical) that connects a Frame Relay device (such as a router) to a Frame Relay switch
Back-to-Back Link A serial link connecting two routers without CSU/DSUs. One router used a DTE cable and the other uses a DCE cable. Typically used in labs.
CSU/DSU Channel Service Unit/Digital Service Unit. A device that knows how to use the layer 1 details of telco Layer 1 serial links that connect to devices such as routers.
DTE Data Terminal Equipment. The DTE synchronizes its clock based on the DCE clock. (Layer 1). Otherwise it is a device not within the service provider’s network (like a routher).
DS0 Digital Signal Level 0. 64Kbps line from the telco. Used for single voice calls.
DS1 Digital Signal Level 1. 1.544Mbps line inside a telco. Uses 24 DSO channels of its original speed plus a management/framing channel of 8Kbps. Also known as a T1.
Frame Relay A standard data-link protocol to create frame-switched or packet-switched service that uses DTE devices (such as routers) to connect to other devices using one physical connection.
HDLC High-level Data Link Control. Data-link layer protocol.
Packet Switching Term used to reference services that examine the contents of data to make forwarding decisions.
T1 1.544Mbps line inside a telco. Uses 24 DSO channels of its original speed plus a management/framing channel of 8Kbps. Also known as DS1.
PDU OSI Protocol Data Unit. This includes headers and trailers for the current layer and all the encapsulated data, if any. Often used as L#PDU. For example, L2PDU references the Data Link layer data unit.
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OSI Model

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 OSI Layer  Description
 Application  User authentication, software communication
 Presentation  Determines data formats and encryption (ie: JPG, ASCII)
 Session  Defines how to start, end and control conversations
 Transport  Error recovery, data delivery, flow control
 Network   Logical addressing, routing, path determination
 Data Link  Defines rules/protocols for when devices can send its data over mediums and defines format of headers and trailers
 Physical  Cables, lights, electricity, etc.

 

 OSI Layer  Protocol/Specs  Devices
 Application/Presentation/Session  Telnet, FTP, HTTP, VoIP, POP3, SMTP  IDS, Firewall
 Transport  TCP, UDP
 Network  IP  Router
 Data Link  HDLC, PPP, IEEE, Frame Relay  WAP, Switch, Modem
 Physical  RJ-45, IEEE  Hub, Repeater
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TCP/IP Architectural Model

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Here are some more things you need to know for the CCNA exam!

 

 TCP/IP Architectural Model
 Application HTTP, POP3, SMTP
 Transport  TCP, UDP
 Internet  IP
 Network Ethernet, Cabling standards, Frame Relay
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Common Applications & their Port Numbers

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This is a list of common applications and port numbers you need to know for the CCNA exam.

Common Applications
& their Port Numbers
 23  TCP  Telnet
 25  TCP  SMTP
 53  TCP, UDP  DNS
 67,68  UDP  DHCP
 69  UDP  TFTP
 80  TCP  HTTP
 110  TCP POP3
 161  UDP  SNMP
 443  TCP  SSL
 14,384-32,767  UDP  VoIP

Misc:

TCP: Transmission Control Protocol
UDP: User Datagram Protocol

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Is JustAnswer.com a scam?

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I’ve been to your site a few times reading up on various topics and noticed a few links to JustAnswer.com and wanted to take a look. It looks like a nice site to get answers but it is a paid-for service and after a few searches online I found some unhappy customers.

Anyone have experience with JustAnswer.com care to share their feedback?

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Please answer: Why are meta tags dead?

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I know everyone says they aren’t used but why not? What makes search engines not use them anymore?

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Can’t find games in marketplace

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I’m on the marketplace online for Android games and when I find some I like I try to search them on my phone and they don’t show up. A lot of the top 10 free games from the online marketplace won’t show up on my phone.

Thank you

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