Quick Check - 70-680 Exam

1. What is the binary number 00001010 11110000 10101010 01000000 in dotted
decimal notation?

10.240.170.64.

2. Are the IPv4 addresses 192.168.1.200 and 192.168.1.24 on the same subnet? Both
have a subnet mask of 255.255.255.0.


The subnet mask specifies that the final octet holds the host address. Therefore
the first three octets hold the subnet’s network address. In both cases, this is
192.168.1.0, so the computers are on the same subnet.


3. Is 10.0.0.130 a valid IPv4 address on the 10.0.0.0/25 subnet?
quick Check answers

No. The /25 subnet mask specifies 25 ones and therefore 32 – 25 = 7 zeros. Zeros
denote host address. Therefore, the host address is from 0000001 to 1111110
binary (0000000 is the network address and 111111 the broadcast address). In
decimal, this is 1 to 126. So the valid IPv4 addresses on the network are 10.0.0.1
to 10.0.0.126. 10.0.0.130 is not in this range and therefore is not valid on this
subnet. It is an address on another subnet (for example, 10.0.0.128/25).