Question

. Who is DBA? What are the major responsibilities of DBA.[1+4]
8. Write short notes on [2*2.5=5]
a) Normalization
b) Coaxial cable

Answer 1

DBA means Database Administrator .

DBA is the person whose main task creating , managing , back ups , securities and privacy of the data in the databases. DBA perform all activities related to maintaing the successful database environment.

Responsibilities of DBA :

Data integrity : The main responsibility of DBA is to ensure that the data is secure from unauthorized access but it is available to the users.

Backup : They ensure that database and data are stored appropriately and can be recovered correctly ,easily and quickly in case of system failure .

Designing of database:  They are responsible for installation, configuration, designing and performance monitoring of the database.

Specialized Data Handling : DBA manage the unstructured data types like documents, video files,images etc with high level skills and additiinal montioring and tuning to maintain its efficiency.

Data extraction and Transformation : The large volume of data that is extracted from the multiple systems import into datawarehouse environment get cleaned up and transformed into desired format to fit into central repository.

(a). NORMALIZATION

The process of minimization of duplicacy or we can say redundancy from the tables or set of relations is known as normalization. It is the process of organizing the data to avoid insertion,update and deletion anomaly. The most commonly used Normal Forms are:

• FNF(first normal form) According to FNF there should be only atomic values in the column of the tables. The order in which data stored do not matter. The value stored should be of same domain and all the columns must have unique name.

SNF( second normal form). For the table to be in SNF the table must satisfy the rule of FNF and should not have partial dependencies

• TNF ( third normal form) The table is in TNF if satisfy the rule of SNF and doesn't have Transitive Dependency.
• BCNF( Boyce and Codd normal form) .For the table to be in BCNF must satisfy the conditions of TNF . BCNF  deals with the certain type of anomalies that are not handled by TNF. The table which do not contain multiple overlapping candidate keys said to be in BCNF.
• If the table is in BCNF and does not have Multivalued Dependency then it is said to be in FOURTH NORMAL FORM.( FNF).

​​​​​​​​​​COAXIAL CABLES :

These are the cables commonly used for cable connections, internet service providing, voice communications .

Coaxials cables has inner conductor of copper that is surrounded by insulating layer. It comprise of outer sheath or jacket serve as conducting shield. The shield design allow the copper conductor to transmit data quickly without any interference. The external layer is of plastic coating that provide security from environmental hazards.

Three most common cable size are RG -58 , RG-11, RG-59.

RG means Radio govt. rating :

RG -58 has impedance of 58W used in thin Ethernet.

RG-11 has impedance of 50W and used in thick ethernet.

RG-59 has impedace of 75 W and use in cable tv.

Applications:

• use in analog communication as it can transmit 10,000 voice signals at a time.
• it is used in cable tv network.
• it is widely use in MAN
• Use in digital telephony as it provide data rate of 600 mps.

Advantage of coaxial cable are :

• they are inexpensive.
• easy to install
• they are very durable
• very easy to expand.
• have very good resistance to EMI

Disadvantage : single cable failure lead to failure of entire network.