If a class B
network on the Internet has a subnet mask of 255.255.248.0, what is the maximum
number of hosts per subnet?
(A) 1022
(B) 1023
(C) 2046
(D) 2047
(A) 1022
(B) 1023
(C) 2046
(D) 2047
Answer
(C)
The binary representation of subnet mask is 11111111.11111111.11111000.00000000. There are 21 bits set in subnet. So 11 (32-21) bits are left for host ids. Total possible values of host ids is 2^11 = 2048. Out of these 2048 values, 2 addresses are reserved. The address with all bits as 1 is reserved as broadcast address and address with all host id bits as 0 is used as network address of subnet.
In general, the number of addresses usable for addressing specific hosts in each network is always 2^N – 2 where N is the number of bits for host id.
The binary representation of subnet mask is 11111111.11111111.11111000.00000000. There are 21 bits set in subnet. So 11 (32-21) bits are left for host ids. Total possible values of host ids is 2^11 = 2048. Out of these 2048 values, 2 addresses are reserved. The address with all bits as 1 is reserved as broadcast address and address with all host id bits as 0 is used as network address of subnet.
In general, the number of addresses usable for addressing specific hosts in each network is always 2^N – 2 where N is the number of bits for host id.
What is the
maximum size of data that the application layer can pass on to the TCP layer
below?
(A) Any size
(B) 2^16 bytes-size of TCP header
(C) 2^16 bytes
(D) 1500 bytes
(A) Any size
(B) 2^16 bytes-size of TCP header
(C) 2^16 bytes
(D) 1500 bytes
Answer
(A)
Application layer can send any size of data. There is no limit defined by standards. The lower layers divides the data if needed.
Application layer can send any size of data. There is no limit defined by standards. The lower layers divides the data if needed.
A computer
on a 10Mbps network is regulated by a token bucket. The token bucket is filled
at a rate of 2Mbps. It is initially filled to capacity with 16Megabits. What is
the maximum duration for which the computer can transmit at the full 10Mbps?
(A) 1.6 seconds
(B) 2 seconds
(C) 5 seconds
(D) 8 seconds
(A) 1.6 seconds
(B) 2 seconds
(C) 5 seconds
(D) 8 seconds
Answer (B)
New tokens are
added at the rate of r bytes/sec which is
2Mbps in the given
question.
Capacity of the
token bucket (b) = 16 Mbits
Maximum possible
transmission rate (M) = 10Mbps
So the maximum
burst time = b/(M-r) = 16/(10-2) = 2 seconds
In the above
formula, r is subtracted from M to calculate the maximum burst time. The reason
for this subtraction is, new tokens are added at the rate of r while
transmission happens at maximum transmission rate M.
Which one of the
following uses UDP as the transport protocol?
(A) HTTP
(B) Telnet
(C) DNS
(D) SMTP
(A) HTTP
(B) Telnet
(C) DNS
(D) SMTP
Answer
(C)
DNS primarily uses User Datagram Protocol (UDP) on port number 53 to serve requests. DNS queries consist of a single UDP request from the client followed by a single UDP reply from the server.
DNS primarily uses User Datagram Protocol (UDP) on port number 53 to serve requests. DNS queries consist of a single UDP request from the client followed by a single UDP reply from the server.
In Ethernet when
Manchester encoding is used, the bit rate is:
(A) Half the baud rate.
(B) Twice the baud rate.
(C) Same as the baud rate.
(D) none of the above
(A) Half the baud rate.
(B) Twice the baud rate.
(C) Same as the baud rate.
(D) none of the above
Answer
(A)
The address of a
class B host is to be split into subnets with a 6-bit subnet number. What is
the maximum number of subnets and the maximum number of hosts in each subnet?
(A) 62 subnets and 262142 hosts.
(B) 64 subnets and 262142 hosts.
(C) 62 subnets and 1022 hosts.
(D) 64 subnets and 1024 hosts.
(A) 62 subnets and 262142 hosts.
(B) 64 subnets and 262142 hosts.
(C) 62 subnets and 1022 hosts.
(D) 64 subnets and 1024 hosts.
Answer
(C)
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