Ccna certification Practice Tests

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 115.  D.  The network for the computer with an IP address of 145.50.23.1/22 is 145.50.20.0/22. 

Its valid range is 145.50.20.1 to 145.50.23.254; the broadcast address for the range is 

145.50.23.255. All of the other options are incorrect.

 116.  C.  RFC 1918 defines three private address ranges, which are not routable on the Internet. 

Although RFC 1819, 1911, and 3030 are real requests for comments, they are all 

irrelevant to IP addressing.

 117.  A.  The private IP address space was created to preserve the number of public IP addresses. 

Private IP addresses are non-routable on the Internet, but this does not make them secure. 

Private IP addresses do not keep communications private, as their name implies. Private 

IP addresses are not publicly addressable for communications. Private IP addresses do not 

allow for an easier setup than public IP addresses.

 118.  D.  Network Address Translation (NAT) is required to communicate over the Internet 

with private IP addresses. Although Internet routers are required for routing, by default 

they will not route private IP addresses to public IP addresses. An IPv4 tunnel or VPN 

tunnel is not required for communications on the Internet with private IP addresses.

 119.  A.  The Class A private IP address range is defined as 10.0.0.0/8. The address range is 

10.0.0.0 to 10.255.255.255. The network IDs 10.0.0.0/10 and 10.0.0.0/12 are wrong 

because the network mask is incorrect. The network ID 172.16.0.0/12 is the private IP 

address range for a Class B network.

 120.  C.  The Class B private IP address range is defined as 172.16.0.0/12. The address range 

is 172.16.0.0 to 172.31.255.255. The network ID 10.0.0.0/8 defines a Class A private IP 

address range. Both the 10.0.0.0/12 and 10.0.0.0/10 network IDs are incorrect.

 121.  C.  Although a Class C address has a classful subnet mask of 255.255.255.0, the private IP 

address range put aside for Class C addresses is 192.168.0.0 to 192.168.255.255, written 

in CIDR notation as 192.168.0.0/16. All of the other options are incorrect.

 122.  D.  Any address in the range of 169.254.0.0/16 is a link-local address. It means that the 

computer has sensed that a network connection is present, but no DHCP is present. 

The network only allows local communications and no routing. Microsoft refers to this 

as an Automatic Private IP Addressing (APIPA) address. If the network jack was not 

working, then the computer would not sense a connection. Although it is possible to have 

a 169.254.0.0/16 address configured on the laptop, it is not probable because it is an 

automatic address. The conclusion that the network is configured properly is incorrect 

because there is no server or device serving DHCP.

 123.  D.  198.168.55.45 is a valid IPv4 public address. All of the other addresses are RFC 1918 

compliant and thus non-routable on the Internet.

 124.  A.  IANA, or the Internet Assigned Numbers Authority, is the governing body that 

distributes public IP addresses and registers them to ISPs. A Request for Comments (RFC) 

is an academic paper that is published to the Internet Advisory Board (IAB). The RFC is 

then voted upon and can become a standard or informational or deemed a best current 

practice, just to name a few. The Internet Engineering Task Force is a group of engineers 

that have helped form protocols used on networks as well as aspects of the Internet.

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