In which of the random-access method, stations do not sense the medium?
ALOHA
ETHERNET
CSMA/CA
CSMA/CD
Correct Answer :
A. ALOHA
Related Questions
Tape storage is referred to as
sequential access storage
direct access storage
random access storage
none of the above
A type of query that is placed within a WHERE or HAVING clause of another query is called
Super query
Sub query
Master query
Multi-query
A ………… clause permits a view definition to be used in multiple places within a query.
where
exist
with
select
Select the incorrect statement
View is derived from other tables.
Once a transaction has executed commit work its effect cant be undone by rollback work .
The input to the aggregate function avg can be non numeric data types
A primary key can never be null.
Select the incorrect statement(s)
i) Foreign key values can be left blank
ii) In SQL duplicates may be present
iii) Theta join operation doesnt remove duplicate columns.
iv) NULL value means string of blank characters.
i ,iii only
ii, iv only
iii, iv only
ii, iii, iv
Transaction access data using two operations
read(), print()
read(), write()
scan(), write()
none of the above
A transaction is said to have terminated if it has
either committed or aborted
either partially committed or aborted
either committed or failed
none of these
The physical path over which a message travels
Thermal
Medium
Protocol
Impulse
An advantage of the database management approach is
data is dependent on programs.
data redundancy increases.
data is integrated and can be accessed by multiple programs.
none of the above.
The ________ states that a foreign key must either match a primary key value in another relation or it must be null.
entity integrity rule
referential integrity constraint
composite attribute
action assertion
A fragmentation is categorized in
1 part
2 part
3 part
4 part
Which command is used to cancel privileges granted through the GRANT command ?
CANCEL
OVER
STOP
REVOKE
Which one of the following statements is false?
The data dictionary is normally maintained by the database administrator.
Data elements in the database can be modified by changing the data dictionary.
The data dictionary contains the name and description of each data element.
The data dictionary is a tool used exclusively by the database administrator.
A DBMS query language is designed to
support end users who use English-like commands.
support in the development of complex applications software.
specify the structure of a database.
all of the above.
The language used in application programs to request data from the DBMS is referred to as the
DML
DDL
VDL
SDL
If the .................... is too much, the receiver may not be able to detect the signal at all or the signal may fall below the noise level.
Noise
Delay
Dispersion
Attenuation
Triggers are also called
active rules
passive rules
inferences
none of the above
UML is stands for
Universal Modeling Language
Unified Modeling Language
United Modeling Language
Uni Modeling Language
The ability to modify the conceptual schema without causing any change to the application program is known as
Physical data independence
Logical data independence
External data independence
Static data
The class based addressing is known as
Classless addressing
Classful addressing
Classified addressing
Classical addressing
In an Entity-Relationship Diagram Diamonds represents
Attributes
Multi-valued attributes
Weak entity set
Relationship sets
The physical location of a record is determined by a mathematical formula that transforms
a file key into a record location is :
B-Tree File
Hashed File
Indexed File
Sequential file.
Select the incorrect statement(s)
i) Shared locks are compatible with each other.
ii) A relation which is in 3NF may have redundancy due to composite keys.
iii) A table in a database can have multiple indexes.
i only
ii, only
ii, iii only
none of the above
In defining the notion of the tuple variable, which one of the clause is useful?
as
by
from
none of the above
Encoding method which does not provide for synchronization
B8ZS
Manchester
RZ
NRZ-L
Which of the following is not a database object?
index
sequence
cursor
trigger
DECLARE is a(an)
executable statement.
declarative statement.
Ordered file
none of the above
The left outer join takes all tuples
in the left relation which didnt match with any tuple in right relation
in the left relation which matched with a tuple in right relation
in the right relation which didnt match with any tuple in left relation
in the right relation which matched with a tuple in left relation
Select the incorrect statement
BCNF is stronger than 3NF
Relational algebra is a non-procedural language
Every conflict serializable schedule is view serializable.
none of the above
Transaction processing is associated with everything below except
producing detail, summary, or exception reports.
recording a business activity.
confirming an action or triggering a response.
maintaining data.