TECHNICAL ENGINEER EXAMINATION (NETWORK)(AFTERNOON, PART 1) doc

[List of Question Contents] Question SOHO environment [Description] Sub-Question 2 1 Basic knowledge regarding ISDN users and network interfaces Sub-Question 3 1 Basic knowledge reg

2001 Autumn

Technical Engineer Examination (Network)(Afternoon Part 1)

Questions must be answered in accordance with the following:

Question Nos Q1 to Q4

Question Selection Select three of the above four

Examination Time 12:30-14:00 (90 minutes)

Instructions:

1 Use an HB pencil If you need to change an answer, erase your previous answer completely and neatly Wipe away any eraser debris

2 Mark your answers in accordance with the instructions below

(1) Examinee Number

Write your examinee number in the space provided, and mark the appropriate space below each digit

(2) Date of Birth

Write your date of birth (in numbers) exactly as it is printed on your examination admission card, and mark the appropriate space below each digit

(3) Answers

In the Selection column, circle the numbers of the questions that you are choosing to do Any question that is not circled will not be scored If you circle all four questions, only the first three will be scored

(4) Write each answer in the space specified for that question

(5) Write your answers clearly and neatly Answer that is difficult to read will receive a lower score

[List of Question Contents]

Question

SOHO environment

[Description]

Sub-Question 2

(1) Basic knowledge regarding ISDN users and network interfaces Sub-Question 3

(1) Basic knowledge regarding DHCP servers (2) Correctly sequencing sentences that describe the operations of a DHCP server and client

(3) Method for detecting duplicate IP addresses

functions using a SOHO router [Illustration]

Sub-Question 2

(2) Completing an ISDN connection configuration [Calculation]

Sub-Question 1 ISDN communication charges

Q2

Expanding an

application system

that uses mobile

communication

equipment

[Description]

Sub-Question 1

(1) Basic knowledge regarding communication interfaces (2) Hardware used to establish a TCP connection Sub-Question 3

(1) Effect on existing network (2) Details regarding changing the address of a Web server and its relocation

(3) Bottleneck when using PDAs, effect on users, and measures to prevent this

[Calculation]

Sub-Question 2

(1) Communication charges per query when using mobile telephones

(2) Communication charges per query when using PDAs (3) Number of queries beyond which communication charges for a mobile telephone become cheaper than using a PDA

system operation

[Description]

Sub-Question 1 Basic knowledge for implementing services for

communications with customers Sub-Question 2 Details regarding changing settings for automated response mail Sub-Question 3

(1) Router functions required for security (2) Services required for routes that directly connect to an ISP (3) Services required for router connections

Sub-Question 4

(1) Problems which are not resolved even if an outsourcing proposal

is implemented (2) Reason why checking for viruses continues for the in-house mail server

(3) Reason why problems are resolved by dividing the firewall into two devices

Q4

Designing a network

focusing on route

design

[Description]

Sub-Question 1

(1) Basic knowledge regarding user authentication procedures (2) Function that allows connections from outside even when the authentication server fails

Sub-Question 2

(1) Basic knowledge regarding routing (2) Changes in the routing table when a router fails

Q1 Read the following question regarding the construction of a SOHO environment and answer

sub-questions 1 through 4

Mr A runs a real estate company and has an office near a train station A PC was installed

in his office several years ago It is used for managing pieces of real estate and customers Now it was decided to change the system to a client-server model, and Mr A started to consult with Company B, with which he has had a close relationship for a long while After meeting many times regarding the system, Mr A made an additional request He wanted to have the system connected to the Internet so that he can contact landlords and obtain industry information

Mr C is in charge of Company B and immediately proposed the system configuration shown in Fig 1

Fig 1 System Configuration Proposed by Company B

The following is a conversation between Mr A and Mr C

Mr C: I have been working on your request for the system to be connected to the Internet, and I

have come up with the system configuration shown in Fig 1

Mr A: Let’s check it over I can use the Internet even if the application server stops?

Mr C: Yes, that’s not a problem Let me explain this configuration The hub of the configuration I

proposed previously is replaced by a SOHO router that has both hub functions and ISDN connection functions This SOHO router will be connected to the ISDN line currently used with your fax machine

Mr A: How much is this going to cost?

Mr C: The cost per month is approximately as follows The connection to the ISP is $20 per

month and the basic charge for the ISDN line does not change Since the access point to the ISP is in the city, the communication charge during connections is ¢8 per 3 minutes So

if you view web pages 30 minutes per day, and assuming that there are 25 work days per month, it will cost $ a

ISP ISDN

Application server Client

Client

Office

SOHO router

Similarly, the cost of reading e-mails will be b if you read them eight times per day, two minutes each time, 25 days per month

Mr A: Is a TA required to connect the ISDN line to the SOHO router?

Mr C: No, it’s not necessary A TA is a terminal adaptor I’ll explain its role using this figure

Fig 2 Reference Configuration for ISDN Users with Network Interface

Mr C: Fig 2 shows the reference configuration for ISDN users with network interface as defined

by a standards organization NT1 in this figure is specifically called a c TE2 refers to something other than a terminal which has been designed for use as a d The device required to connect NT2 and NT1 to this type of terminal is a TA Point R refers to the e point between the TA and TE2

Although the router is a piece of hardware used to connect a different f , as shown

in the figure, a TA is not required if you are equipped with an ISDN interface such as that

of the SOHO router which will be installed

Table SOHO Router Interface Specifications (Excerpt)

Interface Description

Standard IEEE802.3 Connector 8-pin modular jack LAN interface

Number of ports 5

Connector 6-pin modular jack ISDN interface (Point U)

Number of ports 1

Connector 8-pin modular jack ISDN interface (Point S/T)

Number of ports 2

U T

S R

ISDN

Mr A: I think I understand, but I still don’t understand completely Can you explain what kind of

configuration the system will have if this SOHO router is used?

Mr C: That’s shown in Fig 3 TE1 is a piece of hardware that supports ISDN It is equivalent to a

fax machine

Fig 3 Connection Configuration Drawn by Mr C

Mr A: Okay, I get it Now I finally understand the meaning of “point S/T” in that SOHO router

catalog

Mr C: The SOHO router has many various functions, and we will be using the DHCP server

function in your system

Mr A: What is DHCP?

Mr C: We could use a special protocol if your system were just an application system We will

use TCP/IP so that you can use the Internet Hardware connected to the LAN will be assigned IP addresses and addresses must be set for the DNS and gateway Use of DHCP makes these settings and hardware management easy Although it is also possible to use the application server as a DHCP server, the SOHO router will be used as the DHCP server out of consideration of operating conditions and requirements It may take a little while, but I will describe DHCP to you

The following is a summary of Mr C’s description

DHCP is an expansion of the g protocol used so that clients can automatically read network-related settings from a server It contains the added capability of dynamically assigning address information and other configuration information IP addresses are assigned as follows: Note that lines ¦ through ¢ below are out of order because sequencing them in the right order is to be asked by a sub-question

¦ The client sets the server ID and IP address and sends a DHCPREQUEST to the server

U Omitted because this is the answer

to a sub-question

TE1 (fax)

NT1

The client broadcasts DHCPDISCOVER in order to find the server The value of the destination MAC address in this frame is h

¡ The server returns DHCPACK when the pooled IP addresses are i and returns DHCPNAK in all other cases

¢ The server returns DHCPOFFER

Finally, the client checks consistency, and if there are no problems, finishes configuring the system The consistency check includes checking for duplicate IP addresses by using

an ARP request

The IP address is released by sending DHCPRELEASE to the server if the client has finished using it before j of the IP address

Mr A: Okay, I understand Thank you for explaining it so well to the novice I will let you do the

system construction

Mr C: Thank you

Sub-Question 1

Fill in the appropriate answers for boxes a and b in the text

Sub-Question 2

Answer the following questions regarding ISDN

(1) Fill in the appropriate answers for boxes c through f in the text (2) Complete Fig 3 used by Mr C Be sure to insert the correct hardware name in the parentheses and indicate Point S and Point T

Sub-Question 3

Answer the following questions regarding the DHCP server

(1) Fill in the appropriate answers for boxes g through j in the text (2) Re-arrange lines ¦ through ¢, used to describe the operation between the server and the client, in the correct order

(3) Explain in 80 words or less how duplicate IP addresses are detected Be sure to use the keywords “ARP request”, “the client’s own IP address”, and “client”

Sub-Question 4

Explain in 60 words or less which operating requirements caused Company B to propose that the DHCP server function be assigned to the SOHO router rather than to the application server

Q2 Read the following description regarding expansion of a sales information system that uses

mobile communication hardware, and answer sub-questions 1 through 3

Company E manages sales information using an application server and a Web server This sales system provides information regarding products, delivery dates and customers to sales personnel When used inside the office, the application server is accessed from client software running on a PC Some sales personnel also use the system from outside the office by accessing a Web server using HTTP from a browser running on a notebook PC When accessed this way, the Web server creates screens by dynamically using HTML while communicating with the application server In addition, some information which is not updated frequently (hereafter referred to as “local data”) is already downloaded to the

PC inside the office so that it can be accessed from places the salesman visits

Currently, Company E is studying the possibility of expanding this sales system Instead of notebook PCs, which take time to prepare for access, the new system will use new mobile communication devices The possible candidates for filling this role are a mobile telephone with a data display function (hereafter referred to as “mobile telephone”) or a PDA (Personal Digital Assistant) In addition, it is planned to enable all sales personnel to use the sales system from outside the office

The following figure shows the network configuration of the sales information system

Fig Network Configuration of the Sales Information System

Web

PC

PDA

PC PHS

DMZ LAN

RAS GW

RAS: Remote access server

GW server: Gateway server

Note: Parts of the system inside dotted lines are still being investigated

In-house LAN

Applica-tion server Web server

Firewall

GW server 2

Company E

network

telephone

PHS network

Notebook PC

The in-house LAN has a private address and is connected to the Internet using a leased line through a firewall which uses IP filtering The system is also connected to the PHS network through a RAS which is located in the DMZ The RAS has as many ports as there are sales employees who will use the system

Since new mobile communication equipment uses screen data having a unique format, a

GW server is required to convert HTML screen data into screen data in this format The amount of data communicated between the GW server and the new mobile communication equipment is reduced to 50% of the current amount of data communicated using HTML and HTTP In the proposal which uses mobile telephones GW Server 1 at the communication service provider will be used If PDAs are used, GW Server 2 will be installed inside the office

Since mobile telephones cannot store data, the use of local data becomes a problem On the other hand, local data can be stored in the built-in memory of a PDA In addition, PDAs have the external interface outlined in Table 1

Table 1 External Interface of a PDA

IrDA (specifications for SIR, IrLAP, IrLMP, etc defined by IrDA) Built-in

TIA/EIA-232-E PIAFS (PHS Internet Access Forum Standard) External

ITU-T V.34

[Communication Costs]

Company E produced a prototype of the query screen to be used by the new mobile communication equipment using HTML and accessed the prototype screen on the Web server from a notebook PC Results are given in Table 2 When communication costs were calculated using this data, it was assumed that communication time lengths would be the same as given in Table 2 regardless of the mobile communication equipment used The communication cost of network service is shown in Table 3

Table 2 Communication Time Lengths and Amount of Data Required

for a Single Query

Communication time (the time from when a PHS network call

was established until it was disconnected) 90 seconds

Table 3 Communication Costs of Network Service

Item Mobile telephone network PHS network Communication charges (variable cost) ¢0.3/128 bytes ¢1/60 minutes

[Proposal Comparison]

The following is a conversation between Mr F and Mr G Mr F is the network engineer responsible for studying the network configuration and Mr G is his superior

Mr G: I wonder if local data can be used by mobile telephones and PDAs

Mr F: Since mobile telephones cannot store local data, when it is required it will be necessary to

access the data on the application server from outside the company

Mr G: Is it the same when using PDAs?

Mr F: No Local data can be stored in PDA memory Local data does not all change every day If

PDAs are used, data loaded on a salesman’s notebook PC can be transferred to the PDA The amount of data transferred can be reduced through a combination of data compression and a Based on trial calculations, the amount of data transferred per operation is 1/100 of the total amount of local data

Mr G: PDAs have many interfaces Can you explain them to me?

Mr F: IrDA is a data communication standard which uses b TIA/EIA-232-E is

originally intended as an interface between DTE and c If we use PDAs, we will use IrDA inside the office Outside the office, we will use either PIAFS, which is a communication standard especially for the PHS network, or ITU-T V.34, which is a

d standard Of the two, half of sales personnel use the e interface card for digital communications on their notebook PCs In the proposed plan to use PDAs, it seems we will be able to continue using this interface card, so we expect that the same mechanisms as available with the notebook PCs will be used for connecting to RAS and caller authentication

Mr G: In the future, all sales personnel will use this system I'm concerned about the cost

Mr F: I have calculated the cost per query If the system is to be used heavily, it is cheaper to use

mobile telephones

Mr G: Tell me about the effect on the existing network

Mr F: In both the proposals, it is necessary to change the settings of f In the proposal to

use g , it is necessary to change the IP address of the web server and to move it at the same time In another proposal, these changes do not need to be made