The types of noiseless channels are
i) Selective Reject ARQ
ii) simplest protocol
iii) Go-Back-N ARQ
iv) Stop-and-Wait Protocol
i, ii only
ii and iv only
ii and iv only
i, iv only
Correct Answer :
C. ii and iv only
Related Questions
In defining the notion of the tuple variable, which one of the clause is useful?
as
by
from
none of the above
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
Extended Entity Relationship model consists of which of the following
i) Specialization
ii) Generalization
iii) Categorization
i and ii only
ii and iii only
i and iii only
All i, ii iii
Tape storage is referred to as
sequential access storage
direct access storage
random access storage
none of the above
Size of source and destination address in IP header
4 bits
8 bits
12 bits
32 bits
A ………… clause permits a view definition to be used in multiple places within a query.
where
exist
with
select
A fragmentation is categorized in
1 part
2 part
3 part
4 part
Radio frequencies below ............. are more suitable for omnidirectional applications.
300MHz
1GHz
5GHz
10 GHz
Which of the following is true statement ?
SQL permits attribute names to be repeated in the same relation.
a SQL query automatically eliminates duplicates.
a SQL query will not work if there are no indexes on the relations
None of these
Mail services are available to network users through the
Session layer
Presentation layer
Application layer
Transport layer
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.
What is the result of the following SQL statement ?
SELECT A.emp_Name, B.ph_num
FROM emp A LEFT OUTER JOIN phone B
ON A. emp_ID = B.emp_ID
A list of employees phone number
A list of all employees that have spouses, with phone number included in the list
A list of all employees names, including the phone number if they have one
Two lists : One list of employees, the other of phone numbers
Select the correct statement
i) Aggregate functions work on a group of data and return a single value.
ii) ODBC connects the frontend with the database without considering its compatibility
iii) View definition cant be used at multiple places through with clause .
i and ii only
ii and iii only
i and iii only
i only
Full form of CIDR
Classful Inter Domain Routing
Classless International Domain Routing
Classless Inter Domain Routing
none of these
The union of primary keys of a related entity becomes …………. Of a relation.
primarykey
superkey
candidatekey
foreignkey
Which of the following extracts its data from the result of an SQL SELECT statement.
View
Synonym
Sequence
Transaction
Natural mask for a Class A network
255.0.0.0
255.255.0.0
255.255.255.0
none of these
Which of the following is/are error-free channel(s)
i) Noisy channel
ii) Noiseless channel
i only
ii only
Both
None of these
In mesh topology, if the number of devices is n , then the number of ports present in each device is
n
n+1
n-1
n/2
Which of the following produces the relation that has attributes of R1 and R2
Cartesian product
Difference
Intersection
Product
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.
Which of the following is logical topology?
Bus
Ring
Star
None of these
A table that displays data redundancies yields ____________ anomalies
Insertion
Deletion
Update
All of the above
Multivalued dependency is removed in
4 NF
3 NF
2 NF
1 NF
The raw facts and figures are:
Data
Data field
DBMS
DBASE
Disk storage is referred to as
sequential access storage
direct access storage
random access storage
none of the above
The language used in application programs to request data from the DBMS is referred to as the
DML
DDL
VDL
SDL
Three SQL, DDL, CREATE commands are
Schema, Base and Table
Schema, Table and View
Base, Table and Schema
Key, Base and Table
Triggers are also called
active rules
passive rules
inferences
none of the above
............... noise is caused by the random motion of the electrons in a wire and is avoidable.
Thermal
Intermodulation
Cross talk
Impulse