In
the IPv4 addressing format, the number of networks allowed under Class C
addresses is
(A) 2^14
(B) 2^7
(C) 2^21
(D) 2^24
(A) 2^14
(B) 2^7
(C) 2^21
(D) 2^24
Answer
(C)
In class C, 8 bits are reserved for Host Id and 24 bits are reserved for Network Id. Out of these 24 Network Id bits, the leading 3 bits are fixed as 110. So remaining 21 bits can be used for different networks
In class C, 8 bits are reserved for Host Id and 24 bits are reserved for Network Id. Out of these 24 Network Id bits, the leading 3 bits are fixed as 110. So remaining 21 bits can be used for different networks
Which
of the following transport layer protocolss is used to support electronic mail?
(A) SMTP
(B) IP
(C) TCP
(D) UDP
(A) SMTP
(B) IP
(C) TCP
(D) UDP
Answer
(C)
Consider
a source computer (S) transmitting a file of size 106 bits to a destination
computer (D) over a network of two routers (R1 and R2) and three links (L1, L2
and L3). L1 connects S to R1;L2 connects R1 to R2; and L3 connects R2 to D. Let
each link be of length 100km. Assume signals travel over each link at a speed
of 10^8 meters per second. Assume that the link bandwidth on each link is
1Mbps. Let the file be broken down into 1000 packets each of size 1000 bits.
Find the total sum of transmission and propagation delays in transmitting the
file from S to D?
(A) 1005ms
(B) 1010ms
(C) 3000ms
(D) 3003ms
(A) 1005ms
(B) 1010ms
(C) 3000ms
(D) 3003ms
Propagation delay to travel from S to R2 =
(Distance) / (Link Speed) = 10^5/10^8 = 1ms
Total prorogation delay to travel from S to D = 3*1 ms = 3ms
Total prorogation delay to travel from S to D = 3*1 ms = 3ms
Total Ttransmission delay for
1 packet = 3 * (Number of Bits) / Bandwidth = 3*(1000/10^6) = 3ms.
The
first packet will take 6ms to reach D. While first packet was reaching D, other
packets must have been processing in parallel. So D will receive remaining
packets 1 packet per 1 ms from R2. So remaining 999 packets will take 999 ms.
And total time will be 999 + 6 = 1005 ms
Consider
different activities related to email.
m1:Send an email from a mail client to mail
server
m2:Download an email from mailbox server to
a mail client
m3:Checking email in a web browser
Which
is the applicable level protocol user in each activity?
(A) m1:HTTP, m2:SMTP, m3:POP
(B) m1:SMTP, m2:FTP, m3:HTTP
(C) m1:SMTP, m2:POP, m3:HTTP
(D) m1:POP, m2:SMTP, m3:IMAP
(A) m1:HTTP, m2:SMTP, m3:POP
(B) m1:SMTP, m2:FTP, m3:HTTP
(C) m1:SMTP, m2:POP, m3:HTTP
(D) m1:POP, m2:SMTP, m3:IMAP
Answer
(C)
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