MASTER IN ELECTRICAL AND COMPUTERS ENGINEERING
EEC0048 | COMMUNICATIONS SERVICES| Exam template
Duration: 2h00min
Name:.............................................................................................................
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Write the name and number in the header of all sheets of examination to deliver;
Provide the answers on their examination paper in the order of the corresponding
statement;
Read carefully the entire exam and try to answer clear and concisely.
Group I – (20%) Indicate for each statement if it is true or false; completely rewrite the false statement with the necessary corrections to be true. The correction of a false statement using only the negation of it, is not accepted. Generally, to build a true statement just need to change or add one to three words on the false statement. 1. The IMAPv4 protocol is implemented in SMTPS communication service for sending messages to a remotely located mailbox. 2. An Internet domain can only have configured on the DNS maps of its primary server a MX record. 3. The SMTPS service allows sending files without requiring sender authentication. JOÃO NEVES
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MASTER IN ELECTRICAL AND COMPUTERS ENGINEERING
EEC0048 | COMMUNICATIONS SERVICES| Exam template
Duration: 2h00min
4. The e‐mail service depends on the DNS service to verify whether the message sender is online. 5. The e‐mail service supported by X.400 is a synchronous service. 6. HTTP is a protocol that allows transfer, describe the content, formatting and how to display a web page. 7. A Web proxy have to implement only the functionality provided to the server that is supposed to contact. 8.
JOÃO NEVES
A session established between a browser and a web server keeps active until it sent the last message with browser requests. | PAGE 2 / 6
MASTER IN ELECTRICAL AND COMPUTERS ENGINEERING
EEC0048 | COMMUNICATIONS SERVICES| Exam template
Duration: 2h00min
9. The XHTML protocol uses TCP as the transport protocol. 10. SIP is the transport protocol used in VoIP service. JOÃO NEVES
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MASTER IN ELECTRICAL AND COMPUTERS ENGINEERING
EEC0048 | COMMUNICATIONS SERVICES| Exam template
Duration: 2h00min
Group II – (45%) Objectively and succinctly answer the following questions, justifying all the answers: 1.
Compare the e-mail service offered by IMAP and POP protocols, indicating
advantages, disadvantages and potential security problems. 2.
Describe the features of the different types of web proxy you know. Explain the advantages and possible disadvantages in using. 3.
Describe the features offered by the protocols RTSP, SIP and SIP, focusing on different applications of each. 4.
Describe the transport mechanism used by Skype for the communication between users, including interaction with eventual firewalls. 5.
Presents the architecture of the VoIP service support infrastructure, based on Asterisk solution, making reference to the necessary and relevant entities. JOÃO NEVES
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MASTER IN ELECTRICAL AND COMPUTERS ENGINEERING
EEC0048 | COMMUNICATIONS SERVICES| Exam template
Duration: 2h00min
Group III – (35%) Consider the following network infrastructure Olare Lda company. The main features of are as follows: 
All network services are supported in the TCP/IP protocol stack; 
All routers exchange routing information with each other and use the SW‐B as default gateway and access to ISP; 
The router/switch SW1 and SW3 and the router GW2 interconnect three buildings of the company; 
To ensure essential services in the event of failure of the high‐speed circuits, routers are interconnected, in a triangle, by 10 Mb/s links; SW11
GW2
SW1
SW-B
SW12
INTERNET
SW3
SW31
SW32
1.
The company Olare Lda plans to implement its e‐mail service to meet the following characteristics: 
The group receives e‐mail for domain olare.pt; 
Internally the mail is redistributed by three domains that are invisible from the outside: olare-si.pt, olare-cf.pt and olare-id.pt; 
The three domains should be available at all company facilities; 
The e‐mail users should have access to inboxes being in roaming on the Internet or local in each building. a) Present the solution that would implement to solve this problem, indicating the servers and protocols chosen for each of the JOÃO NEVES
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MASTER IN ELECTRICAL AND COMPUTERS ENGINEERING
EEC0048 | COMMUNICATIONS SERVICES| Exam template
Duration: 2h00min
requirements. Complements the solution with a possible configuration of network infrastructure. b) Indicate the requirements and the necessary settings on the DNS service to allow the requirements of the internal and external e‐mail service. c) Which solution would you choose to implement security and reliability requirements in this e‐mail solution? d) Considering the performance of the available hardware, Olare Ltd company decided to virtualize the e‐mail service support servers, implementing redundancy to improve the quality of service. Describe a possible solution to this virtualized infrastructure, from the network access features to the processes in the operating system to choose. END
JOÃO NEVES
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