Certification Questions

Q:

In the following pieces of code, B and D will compile without any error. True or false ?

A: StringBuffer sb1 = "abcd";

B: Boolean b = new Boolean("abcd");

C: byte b = 255;

D: int x = 0x1234;

E: float fl = 1.2;

A) TRUE B) FALSE
Answer & Explanation Answer: A) TRUE

Explanation:

The code segments B and D will compile without any error. A is not a valid way to construct a StringBuffer, you need to create a StringBuffer object using "new". B is a valid construction of a Boolean (any string other than "true" or "false" to the Boolean constructor will result in a Boolean with a value of "false"). C will fail to compile because the valid range for a byte is -128 to +127 (i.e., 8 bits, signed). D is correct, 0x1234 is the hexadecimal representation in java. E fails to compile because the compiler interprets 1.2 as a double being assigned to a float (down-casting), which is not valid. You either need an explicit cast, as in "(float)1.2" or "1.2f", to indicate a float.

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7 7503
Q:

Which layer of the OSI model offers three different modes of communication : Simplex, half duplex, and full duplex?

A) Presentation B) Transport
C) Application D) Session
 
Answer & Explanation Answer: D) Session

Explanation:

The Session layer of the OSI model offers three different modes of communication : Simplex, half duplex, and full duplex.

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1 7402
Q:

What protocol would you use if you were running xDSL and needed authentication?

Answer

PPPoE  or  PPPoA

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Subject: CCNA

5 7401
Q:

Which of the following descriptions about IPv6 is correct?

A) Addresses are not hierarchical and are assigned at random B) Broadcasts have been eliminated and replaced with multicasts
C) There are 2.7 billion addresses D) An interface can only be configured with one IPv6 address
 
Answer & Explanation Answer: B) Broadcasts have been eliminated and replaced with multicasts

Explanation:

There are no broadcasts with IPv6. Unicast , multicast, anycast, global, and link - local unicast are used.

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1 7305
Q:

You have the following binary number :10110111. What are the decimal and hexadecimal equivalents?

A) 69/0x2102 B) 183/B7
C) 173/A6 D) 83/0xC5
 
Answer & Explanation Answer: B) 183/B7

Explanation:

You must be able to take a binary number and convert it into both decimal and hexadecimal. To convert to decimal, just add up the 1s using their values. The values that are turned on with the binary number of 10110111 are 128+32+16+4+2+1=183. To get the hexadecimal equivalent, you need to break the eight binary digits into nibbles (4 bits), 1011 and 0111. By adding up these values, you get 11 and 7. In hexadecimal, 11 is B, so the answer is 0xB7.

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1 7093
Q:

What is the subnetwork address for a host with the IP address 200.10.5.68/28?

A) 200.10.5.56 B) 200.10.5.32
C) 200.10.5.64 D) 200.10.5.0
 
Answer & Explanation Answer: C) 200.10.5.64

Explanation:

This is a pretty simple question. A/28 is 255.255.255.240, which means that our block size is 16 in the fourth octent. 0,16, 32, 48, 64, 80, etc. The host is in the 64 subnet.

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1 7083
Q:

An administrator issues the command "ping 127.0.0.1" from the command line prompt on a PC host named PC1. If an ICMP reply is received, what does this confirm?

A. The PC host PC1 has connectivity with a local host
B. The PC host PC1 has connectivity with a Layer 3 device
C. The PC host PC1 has a default gateway correctly configured
D. The PC host PC1 has connectivity up to Layer 5 of the OSI model
E. The PC host PC1 has the TCP/IP protocol stack correctly installed

Answer

Answer : E

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Subject: CCNA

11 7083
Q:

A receiving host has failed to receive all of the segments that it should acknowledge. What can the host do to improve the reliability of this communication session?

A) Send a different source port number B) Restart the virtual circuit
C) Decrease the sequence number D) Decrease the window size
 
Answer & Explanation Answer: D) Decrease the window size

Explanation:

A receiving host can control the transmitter by using flow control ( TCP uses windowing by default). By decreasing the window size, the receiving host can slow down the transmitting host so the receiving host does  not overflow its buffers.

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0 7071