Systems, databases, networks

Question 1

The term “atomiticity” regarding database integrity

a.
Tables may only have a single indexed field

b.
Tables may only have a single foreign-key relationship

c.
Primary key attributes must have a single, unique, non-sequential index

d.
Database transactions are indivisible and partial transactions are not allowed

Answer 1

ACID principles (Atomicity, Consistency, Isolation, and Durability) are used to describe reliable, fault-tolerant databases. Atomicity refers to the fact that a database transaction is an atomic event – it must either completely take place or not take place. Consider an “UPDATE” statement that is meant to modify the values of 15,000 rows in a database. If the RDBMS suffers a hardware failure during the update, the system must be able to guarantee that either all 15,000 rows were updates, or none were updated. A partial transaction would lead to potential data inconsistencies. In this sense, the transaction is “atomic” and indivisible.

Question 2

A hospital wants to implement a short-range tracking system for inventory management.

a.
802.11g

b.
Voice Over Internet Protocol (VOIP)

c.
802.11n

d.
Radio Frequency Identification (RFID)

Answer 2

use case described requires a short-range protocol such as RFID. 802.11g and 802.11n are both standards for medium-range wireless local area networks. VOIP is a mechanism for transmitting voice data over internet and would not be used for this scenario.

Question 3

Which of the following is not a feature of relational database management systems?

Select one:

a.
Constraints can be defined that force an attribute to be unique or non-null

b.
Data Definition Language used to describe metadata about the relation

c.
Objects are represented as a multidimensional array to allow rapid lookup of data

d.
Attributes can be indexed to allow for faster retrieval of information

Answer 3

Objects are represented as a multidimensional array to allow rapid lookup of data

Question 4

Consider two tables in a database, named PATIENTS and ENCOUNTERS. The primary key in PATIENTS is an attribute named PAT_ID, which is a foreign key in ENCOUNTERS. The primary key in ENCOUNTERS is an attribute named ENCOUNTER_ID. Which SQL query would return a list of patients and encounters that include patients who had no matches in the ENCOUNTERS table?

Select one:

a.
select patients.pat_id, encounter.encounter_id from patients
left outer join encounter
on patient.pat_id = encounter.pat_id

b.
select patients.pat_id, encounter.encounter_id from patients
full outer join encounter
on patient.pat_id = encounter.pat_id

I
c.
(select * from patients
where pat_id is null)
union
(select * from encounters)

d.
select * from patients
where pat_id in
(select pat_id from encounters)

Answer 4

select patients.pat_id, encounter.encounter_id from patients
left outer join encounter
on patient.pat_id = encounter.pat_id

Question 5

type of UML diagram is represented in this image
a.
Class

b.
Ishikawa

c.
Use Case

d.
Activity

Answer 5

Use Case

Question 6

A user clicks a link on a webpage to direct her internet browser to the web resource identified by the URL http://www.amia.org. The web browser action of requesting and rendering an HTTP web page takes place at which layer of the TCP/IP stack?

Select one:

a.
Transport

b.
Application

c.
Network

d.
Data Link

Answer 6

Correct. In the OSI 7-layer model, the web-browser and HTTP requests are in the Application layer, layer 7. Other protocols that exist at the application layer include POP and IMAP (for email clients) and FTP (for file transfer). Data Link, Network, and Transport layers exist at level 2, 3, and 4 of the OSI 7-layer model, respectively. ARP (Address Resolution Protocol) is an example of a data link address and is a mechanism for translating network layer addresses (an IP address) to link layer addresses (an Ethernet address). DHCP is a network layer protocol for assigning IP addresses to a host. TCP and UDP are Transport layer protocols and differ in many ways. TCP is a connection-oriented protocol for bidirectional communication, and it includes acknowledgement. HTTP requests at the Application layer are transmitted via TCP. In contrast, UDP is a connectionless protocol and does not require acknowledgement. It does not include mechanisms for error-correction (unlike TCP) and is used in DNS and VOIP, as examples.

Question 7

In the MUMPS database and programming language, global variables are designated by
Select one:

a.
A hash symbol (“#”)

b.
A global declaration and percent symbol (“Global%”)

.

c.
An exclamation point (“!”)

d.
An up arrow or caret symbol (“^”)

Answer 7

An up arrow or caret symbol (“^”)