Ccna certification Practice Tests

345

 23.  A.  The command 

ntp source loopback 0 will configure the NTP service to respond to 

clients from the source address of the loopback 0 interface. The command 

ntp loopback 

0 is incorrect. The command ntp master loopback 0 is incorrect. The command ntp 

clock loopback 0 is incorrect.

 24.  B.  The command 

clock set 2:24:00 1 august 2019 will set the clock to 2:24 a.m. 

(24-hour format) and August 1, 2019. The command 

clock set 2:24:00 1 august 

2019 is incorrect when configured from a global configuration prompt. The command 

clock set 2:24:00 august 1 2019 is incorrect. The command clock 2:24:00 1 

august 2019 is incorrect.

 25.  B.  A reverse lookup is when the fully qualified domain name (FQDN) is resolved from an 

IP address. This is useful when you want to identify an IP address. From the IP address, 

you can derive the FQDN. A reverse lookup is not when the request needs to be reversed 

to another DNS server. A reverse lookup is not when the DNS queried can answer the 

request without asking another DNS server. A reverse lookup is not the resolution of an 

FQDN to an IP address; it is the resolution of an IP address to an FQDN.

 26.  C.  The PTR, or pointer record, is used to look up IP addresses and return FQDNs that 

are mapped to them. This is helpful to identify an IP address, and in the case of SSH, it 

is used to positively identify the host you are connecting to. The A record is used to look 

up an IP address for a given hostname. The CName record is used to look up the alias 

for a given hostname. The AAAA record is used to look up an IPv6 address for a given 

hostname.

 27.  A.  The configured DNS domain name is appended to the hostname query. As an example, 

if you query a hostname of routera and the configured domain name is network.local, 

the DNS server will see a query for routera.network.local. The DNS zone is the database 

of records contained in DNS. Host header is a term used with web servers and therefore 

not relevant to DNS resolution. The hostname PTR record is the reverse DNS record for a 

given IP address.

 28.  C.  Static hostname entries are the most secure name resolution method for routers and 

switches because they are configured locally on the device. This is because the switch or 

router does not need to forward-query a server. However, static hostname entries are not 

scalable. DNS is not considered as secure as static hostname entries because it is publicly 

accessible. PTR records are reverse DNS records and therefore not relevant to security. 

Link Local Multicast Name Resolution (LLMNR) is the protocol that the Windows 

operating system uses for local name queries.

 29.  A.  The A record is the DNS record that is queried when you want to resolve a hostname 

to an IP address. The CName record is used to look up the alias for a given hostname. 

The PTR, or pointer record, is used to look up IP addresses and return FQDNs that 

are mapped to them. The AAAA record is used to look up an IPv6 address for a given 

hostname.

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