HappY NeW YeaR - - 2007

Hi Frenz,

Wish U all Happy & Prosperous New Year - 2007

Q & A about PORT

1: What is a header and why is it significant to TCP/IP?

** A header is a series of bits that is prepended to application data by TCP, UDP, and IP. These bits provide essential pieces of information that facilitate the communications between these protocol suites on the source and destination machines during a communications session.

2: What function is served by a port address?

** A port address uniquely identifies the application in a communications session. Two port addresses exist in each communications session: one to identify the source application and the other to identify the destination application.

3: What's the difference between a source port address and a destination port address?

** A source port address identifies the address of the application that initiated the conversation. A destination port address is the address of the recipient of that conversation.

4: What's the difference between a well-known, registered, and dynamic port address?

** A well-known port address can only be assigned to system-level processes. Assignment of well-known port addresses is carefully regulated by IANA, as there are only 1,024 possible addresses. These range from 0 to 1023.

A registered port address is also regulated by IANA, but these numbers can be assigned to applications run by users. Registered port numbers range from 1024 to 49151.

Dynamic port addresses are selected on the fly from a pool of available or unused port addresses. The pool of possible addresses starts at 49151 and runs up to 65535.

5: What are the four most important network-oriented functions provided by IP?

** IP performs four critical functions:

- Creating an envelope for carrying data through a network or internetwork.

- Providing a numeric addressing system that lets you uniquely identify virtually every machine in the Internet around the world.

- Enabling each envelope or data packet to be specifically addressed to its intended destination. This address is the packet's destination IP address.

- Enabling each envelope or packet of data to also tell the recipient machine who sent it. This return address is the source IP address.

6: What are the two most important network-oriented functions provided by UDP?

** UDP's two most critical functions include

- Accepting data from an application and wrapping a UDP header around it. The combined structure of UDP header and application data is known as a datagram. Unlike TCP, UDP doesn't have to segment its data. The type of applications that use UDP are such that only small quantities of data typically are passed at a time to UDP. The datagram is handed to IP for further processing.

- Verifying whether the data in the datagram was damaged in transit. If the data is found undamaged, it is handed to its intended destination application. If the data appears to have been damaged, the entire datagram is discarded.

7: What are the six most important critical network-oriented functions provided by TCP?

** TCP's top six functions include

- Chopping up application data into bite-sized chunks known as segments

- Managing the communications session

- Guaranteeing that data gets delivered to the correct destination machine and application

- Finding and fixing any damage that occurs to data when it traverses the network

- Ensuring that any data lost in transit is replaced

- Reassembling data received into a perfect copy of the application data that was sent

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"May Peace be your gift at Christmas and your blessing all year through!"

Basic Q & A ( switching )

1. What is multilayer switching (MLS)?

** MLS forwards traffic using information from Layer 2, Layer 3, and Layer 4all in hardware at wire speed.

2.What is a collision domain, and where does it exist in a switched LAN?

** A collision domain is a network segment where shared media access is supported. Devices on the shared media must compete for access when transmitting data. In a switched network, the collision domain is restricted to a single switch port and does not extend across the switch.

3. What is a broadcast domain, and where does it exist in a switched LAN?

** A broadcast domain is the extent of a network where broadcast frames propagate. Basically, a broadcast domain covers an area where Layer 2 devices are located and terminates at the boundary of a Layer 3 device. In a switched network, the broadcast domain extends to all switch ports assigned to a common VLAN. This is because a switch forwards broadcasts out all available ports in a VLAN.

4. What is a VLAN, and why is it used?

** A virtual LAN (VLAN) is a group of switch ports that communicate as if they were attached to a single shared-media LAN segment. VLANs can extend across buildings or backbones, as long as the VLAN is connected end to end through trunking or physical connections. A VLAN is a broadcast domain. VLANs segment networks for ease of management and better performance.


5. At what OSI layers do devices in the distribution layer usually operate?

** Layers 2, 3, and 4

6. What is network segmentation? When is it necessary, and how is it done in a campus network design?

** Segmentation is the process of dividing a LAN into smaller, discrete collision domains. If a large percentage of collisions is observed on a LAN, segmentation is appropriate. In a campus network design, segmentation occurs at each switch port. A similar form of segmentation involves reducing the size of broadcast domains. Placing Layer 3 devices in the distribution and core layers terminates the broadcast domains at those layer boundaries.

Basic info about Network Standards

1: What is the IETF?

** The Internet Engineering Task Force (IETF) is responsible for developing and maintaining the Internet's technologies, as well as guiding its growth and development. Consequently, the IETF is frequently regarded as the guardian of the Internet and its technologies.

2: What is the difference between open standards and closed, or proprietary, technologies?

** A closed or proprietary technology is one developed in secret. The details about how it is made or how it works are kept a secret. Conversely, an open technology is one developed publicly and whose technical details are shared freely with anyone who would like to know them.

3: What is interoperability?

** Interoperability is the ability to build a functional networked computing environment by interconnecting products from different manufacturers.

4: What is the benefit of interoperability?

** The benefit of interoperability across vendor platforms is that it makes products from different vendors compatible, thus encouraging price-based competition. The result is that it enables communications between dissimilar computer systems.

5: How do you create and maintain the technical standards that enable the Internet and its technologies to be interoperable?

** The IETF creates and maintains the technical standards that enable the Internet and its technologies to remain interoperable. It does so by sanctioning committees to study problems and develop solutions. The solutions are documented publicly in Requests For Comments (RFCs). Products that conform to the standards set forth in the RFCs interoperate regardless of who made them.

6: What is a reference model and why is it needed?

** A reference model is a logical framework that keeps a sequence of events in proper order. Reference models have been indispensable in developing open networks and systems by providing a neutral framework for all to follow.

7: Explain the concept of logical adjacency.

** Logical adjacency means that two compatible applications function as if they are passing data directly back and forth between each other. For example, you use e-mail software to send e-mails to other people using similar software. In reality, the e-mail software packages communicate indirectly. They communicate directly with TCP/IP. Simply stated, the two e-mail packages appear logically adjacent, even though they physically are not.

IP Addressing Ques (Answer urself )

1. A router can determine that an IP address is part of a Class B network
by examining the first two bits in the IP address. What are the first two
bits for a Class B network?

A. 00
B. 01
C. 10
D. 11

2. What does an IP address of 127.0.0.1 indicate?

A. A local broadcast
B. A directed multicast
C. The local network
D. A local loopback

3. Which of the following subnet masks will support 50 IP addresses?


A. 255.255.255.240
B. 255.255.255.0
C. 255.255.255.192
D. 255.255.255.224

4. VLSM is compatible with which of the following routing protocols?
(Choose all that apply.)

A. RIPv1
B. RIPv2
C. IGRP
D. EIGRP

5. Which of the following best describes route summarization?

A. A router’s ability to take a group of subnetworks and summarize
them as one network advertisement
B. The Cisco IOS feature that permits serial interfaces to borrow an
IP address from another specified interface
C. The ability to tunnel IP address information inside an AURP
encapsulated frame
D. EIGRP’s ability to isolate discontiguous route advertisements from
one AS to another

6. Which of the following best summarizes the networks 172.16.100.0/24
and 172.16.106.0/24?

A. 172.16.0.0/24
B. 172.16.100.0/20
C. 172.16.106.0/20
D. 172.16.96.0/20

7. Which of the following is a good design practice for implementing
route summarization?

A. Use primarily with discontiguous networks.
B. Use primarily with contiguous networks.
C. Do not use with VLSM.
D. Use with non-hierarchical addressing.

8. Which of the following router-configuration commands would you
use to disable automatic route summarization in an EIGRP
environment?

A. no summary
B. no auto-summary
C. no summary stub
D. no route-summary

9. Which of the following are caveats of Cisco’s IP unnumbered IOS feature?
(Choose all that apply.)

A. Does not work over HDLC networks.
B. Is not compatible with SNMP.
C. Does not work over X.25 networks.
D. You cannot ping an unnumbered interface.

10. If you have a subnet mask of 255.255.255.248, what is another way
of displaying this mask?

A. /17
B. /23
C. /27
D. /29

11. Given the VLSM address 172.16.1.8/30, what are the two IP
addresses in the range that may be assigned to hosts?

A. 172.16.1.8
B. 172.16.1.9
C. 172.16.1.10
D. 172.16.1.11

12. Given an IP address of 172.16.0.10/29, what is the network address?

A. 172.16.0.8
B. 172.16.0.9
C. 172.16.0.11
D. 172.16.0.12

13. Which of the following may be done to overcome problems associated
with discontiguous networks?

A. Use route summarization.
B. Use VLSM.
C. Use IP unnumbered.
D. Disable route summarization.

14. Which of the following IP addresses do Cisco routers use to designate
the default route?

A. 1.1.1.1
B. 0.0.0.0
C. 255.255.255.255
D. 127.0.0.1

15. If you decide not to use IP unnumbered on a serial link, to best preserve
IP addresses, what should your subnet mask be?

A. 255.255.255.255
B. 255.255.255.0
C. 255.255.255.252
D. 255.255.252.0

16. What are the two methods that are most commonly used to represent
an IP address?

A. Dotted-decimal
B. Octal
C. Binary
D. Hexadecimal