Thursday, February 26, 2009

TCP/IP and the OSI Reference Model

As illustrated in Figure 1.2, the TCP/IP model consists of four layers, each of which can have several sublayers. These layers correlate roughly to layers in the OSI reference model and define similar functions. Some of the TCP/IP layers correspond directly with layers in the OSI reference model while other span several OSI layers. The four TCP/IP layers are:
...

• The TCP/IP Application Layer refers to communications services to applications and is the interface between the network and the application. It is also responsible for presentation and controlling communication sessions. It spans the Application Layer, Presentation Layer and Session Layer of the OSI reference model. Examples include: HTTP, POP3, and SNMP.
• The TCP/IP Transport Layer defines several functions, including the choice of protocols, error recovery and flow control. The transport layer may provide for retransmission, i.e., error recovery, and may use flow control to prevent unnecessary congestion by attempting to send data at a rate that the network can accommodate, or it might not, depending on the choice of protocols. Multiplexing of incoming data for different flows to applications on the same host is also performed. Reordering of the incoming data stream when packets arrive out of order is included. It correlates with the Transport Layer of the OSI reference model. Examples include: TCP and UDP, which are called Transport Layer, or Layer 4, protocols.
• The TCP/IP Internetwork Layer defines end-to-end delivery of packets and defines logical addressing to accomplish this. It also defines how routing works and how routes are learned; and how to fragment a packet into smaller packets to accommodate media with smaller maximum transmission unit sizes. It correlates with the Network Layer of the OSI reference model. Examples include: IP and ICMP.
• The TCP/IP Network Interface Layer is concerned with the physical characteristics of the transmission medium as well as getting data across one particular link or medium. This layer defines delivery across an individual link as well as the physical layer specifications. It spans the Data Link Layer and Physical Layer of the OSI reference model. Examples include: Ethernet and Frame Relay.

FIGURE: OSI, TCP/IP and NetWare
FIGURE: OSI, TCP/IP and NetWare

CCNA Practice Tests 3.1.0

Publisher's Description:
CCNA Practice Tests - About CCNA - Cisco Certified Network Associate certification is awarded by Cisco(R) Systems on successful completion of CCNA (Exam code: 640-607) exam. CCNA is a foundation level certification offered by Cisco(R). The exam objectives include TCP/IP fundamentals, OSI model, networking fundamentals like Ethernet, Token Ring, FDDI;Cisco IOS fundamentals, and simple router and switch configurations. CCNA is a leading certification in the area of vendor specific certifications in computer networking technologies.
Practice tests for CCNA (Cisco Certified Network Associate) conforms to the latest objectives of the exam. The package contains 225+ questions and most questions carry detailed explanations. The question types presented in the exam simulator include multiple choice, true/false, exhibit based questions. Also, the test engine enables you to review the wrong answers at the end of the exam. Category wise scoring enables the candidate to know the weak areas for further study. CCNA exam also includes simulation questions. As a result, the CCNA practice tests offered by simulationexams.com also incorporate similar simulation exercises to prepare the students to face the certification exam more confidently.

List of Changes:

Version 3.1.0 from 2003-03-06

Minor updates

User License Agreement:

SOFTWARE LICENSE AGREEMENT (END USER LICENSE AGREEMENT)
NOTICE TO USERS: CAREFULLY READ THE FOLLOWING LEGAL AGREEMENT. USE OF THE SIMULATIONEXAMS.COM SOFTWARE PROVIDED WITH THIS AGREEMENT (THE "SOFTWARE") CONSTITUTES YOUR ACCEPTANCE OF THESE TERMS. IF YOU DO NOT AGREE TO THE TERMS OF THIS AGREEMENT, DO NOT DOWNLOAD, INSTALL AND/OR USE THIS SOFTWARE. USER'S USE OF THIS SOFTWARE IS CONDITIONED UPON COMPLIANCE BY USER WITH THE TERMS OF THIS AGREEMENT.
1. LICENSE GRANT. SimulationExams.com grants you a license to use the demo version / full version (if purchased a full version of the software) of the SimulationExams.com software programs (the "SOFTWARE") on any computer as long as the terms of this license agreement are respected. "You" means the company, entity, or individual installing or using the SOFTWARE. "Use" means storing, loading, installing, executing, or displaying the SOFTWARE. You may not modify the SOFTWARE or disable any licensing or control features of the SOFTWARE except as an intended part of the SOFTWARE's programming features. This license is not transferable to any other hardware product or other company, entity, or individual. SimulationExams.com means any entity/individual(s)/Company representing SimulationExams.com.
2. OWNERSHIP. The SOFTWARE is owned and copyrighted by SimulationExams.com and/or any entity/individual representing it. Your license confers no title or ownership in the SOFTWARE and should not be construed as a sale of any right in the SOFTWARE.
3. COPYRIGHT. The SOFTWARE is protected by copyright laws and international treaty provisions. You acknowledge that no title to the intellectual property in the SOFTWARE is transferred to you. You further acknowledge that title and full ownership rights to the SOFTWARE will remain the exclusive property of SimulationExams.com and/or the entity/individual representing it, and you will not acquire any rights to the SOFTWARE except as expressly set forth in this license. You agree that any copies of the SOFTWARE will contain the same proprietary notices which appear on and in the SOFTWARE.
4. UNAUTHORIZED USE. You may not use, copy, rent, lease, sell, modify, decompile, disassemble, otherwise reverse engineer, or transfer the SOFTWARE except as provided in this agreement. Any such unauthorized use shall result in immediate and automatic termination of this license.
5. BUNDLING. In no case may the SOFTWARE be bundled with hardware or other non-shareware software without written permission from SimulationExams.com.
6. DISTRIBUTION. Provided that you verify that you are distributing the Demo version of the SOFTWARE, you are hereby licensed to make as many copies of the Freeware/trial package of the SOFTWARE as you wish; give exact copies of the original Demo/trial package of the SOFTWARE to anyone; and distribute the Demo/trial package of the SOFTWARE in its unmodified form via electronic means (Internet, BBS's, Shareware distribution libraries, CD-ROMs, etc.). You may charge a distribution fee for the package, but you must not represent in any way that you are selling the software itself.
Distribution of the full version of the software (i.e. neither Demo/ Trial) is forbidden.
All distribution of SOFTWARE is further restricted with regard to sources which also distribute virus source code and related virus construction/creation materials. The SOFTWARE may not be made available on any site, CD-ROM, or with any package which makes available or contains viruses, virus source code, virus construction programs, or virus creation material.
Permission to distribute the SOFTWARE is not transferable, assignable, saleable, or franchisable. Each entity wishing to distribute the package must independently satisfy the terms of the distribution license.
7. LIMITED WARRANTY. THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS. SimulationExams.com and/or the entity/individual representing simulationexams.com SOFTWARE DISCLAIMS ALL WARRANTIES RELATING TO THIS SOFTWARE, WHETHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. NEITHER SIMULATIONEXAMS.COM NOR ANYONE ELSE WHO HAS BEEN INVOLVED IN THE CREATION, PRODUCTION, OR DELIVERY OF THIS SOFTWARE SHALL BE LIABLE FOR ANY INDIRECT, CONSEQUENTIAL, OR INCIDENTAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE SUCH SOFTWARE, EVEN IF SimulationExams.com and/or the entity/individual representing SIMULATIONEXAMS.COM HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES OR CLAIMS. THE PERSON USING THE SOFTWARE BEARS ALL RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE.
SOME JURISDICTIONS DO NOT ALLOW LIMITATION OR EXCLUSION OF INCIDENTAL OR CONSEQUENTIAL DAMAGES, SO THE ABOVE LIMITATIONS OR EXCLUSION MAY NOT APPLY TO YOU TO THE EXTENT THAT LIABILITY IS BY LAW INCAPABLE OF EXCLUSION OR RESTRICTION.
IN NO EVENT SHALL ANY THEORY OF LIABILITY EXCEED THE LICENSE FEE PAID TO SimulationExams.com and/or the entity/individual representing SIMULATIONEXAMS.COM.
9. SEVERABILITY. In the event of invalidity of any provision of this license, the parties agree that such invalidity shall not affect the validity of the remaining portions of this license.
10. NO LIABILITY FOR CONSEQUENTIAL DAMAGES. IN NO EVENT SHALL SimulationExams.com and/or the entity/individual representing it, OR ITS SUPPLIERS BE LIABLE TO YOU FOR ANY CONSEQUENTIAL, SPECIAL, INCIDENTAL, OR INDIRECT DAMAGES OF ANY KIND ARISING OUT OF THE DELIVERY, PERFORMANCE, OR USE OF THE SOFTWARE, EVEN IF SIMULATIONEXAMS.COM AND/OR INDIVIDUALS/ENTITIES REPRESENTING SIMULATIONEXAMS.COM HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. IN NO EVENT WILL SimulationExams.com and/or the entity/individual representing SIMULATIONEXAMS.COM, LIABILITY FOR ANY CLAIM, WHETHER IN CONTRACT, TORT, OR ANY OTHER THEORY OF LIABILITY, EXCEED THE LICENSE FEE PAID BY YOU, IF ANY.
11. GOVERNING LAW. This agreement shall be governed by the laws of India, excluding the application of its conflicts of law rules, and shall inure to the benefit of SimulationExams.com and/or the entity/individual representing it, and any successors, administrators, heirs, and assigns. Any action or proceeding brought by either party against the other arising out of or related to this agreement shall be brought only in a COURT of competent jurisdiction located in India. The parties hereby consent to in personam jurisdiction of said courts.
12. INSPECTION AND TESTING. You agree and acknowledge that you will thoroughly inspect and test the SOFTWARE for all of your purposes upon commencement of your use. Any legal action, claim, or any arbitration relating in any way to this agreement or software covered by it must be officially filed or officially commenced no later than 90 days after your first download/installation of the software.
13. SimulationExams.com software is not affiliated with, nor endorsed by, any other company including the following: CompTIA�, Inc; Cisco� Systems, Inc; Microsoft�, Inc; or any other company. All trademarks are trademarks of their respective owners and duly acknowledged. MCSE �, MCSE+I � are registered trademarks of Microsoft� Corporation and CCNA�, CCNP�, CCIE� are registered trade marks of Cisco� Systems. A+�,Network+�, i-Net+�, Server+�are registered trade marks of CompTIA� and duly acknowledged.
14. Every effort has been made to generate unique and original Test Questions and exam material, based only on that
company's published exam objectives. Our goal is to provide an additional mechanism for self-study and
preparation for each exam. All information, test questions, practice exams, databases, software, and related information is provided on an "as-is" basis with no warranty or fitness implied. The Test and Database Authors, SimulationExams.com, any entity/individual associated with SimulationExams.com shall have neither liability nor responsibility to any person or entity with respect to any loss or damages arising from the information contained on this Web Site or from the use of any information or software or database of questions contained in the software.
15. ENTIRE AGREEMENT. This is the entire agreement between you and SimulationExams.com, supersedes any prior agreement or understanding, whether written or oral, relating to the subject matter of this license.
16. RESERVED RIGHTS. All rights not expressly granted here are reserved to SimulationExams.com.

Screenshot:
CCNA Practice tests - SimulationExams.com>

Download Now
File Size: 4 Mb