Ccna certification Practice Tests

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Appendix 

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  Answers to Practice Test Questions

 30.  B.  The time to live, or TTL, limits the amount of time a DNS entry will be available in 

the DNS cache. The TTL can be defined by the DNS administrator on the entry, or it can 

be defined in the SOA record as the default TTL. An A record is used to look up an IP 

address for a given hostname with DNS name resolution. The Start of Authority (SOA) is 

the first record in a DNZ zone that explains where to find other servers and parameters 

for zone operation. The TTL does not default to 5 minutes; the default TTL is defined in 

the SOA record.

 31.  A.  The DHCP acknowledgment message is sent from the DHCP client to the DHCP 

server to acknowledge that the IP address offered will be used by the client. The Discover 

message is the first message that is sent by the client to discover a DHCP server on the 

local network. The Offer message is sent by the DHCP server to offer an IP address lease 

to the client. The Request message is sent from the client to the DHCP server to formally 

request the offered IP address lease.

 32.  A.  DHCP uses layer 3 broadcasts by sending packets to 255.255.255.255 for initial 

DHCP discovery. Layer 3 multicast is not used for DHCP clients. Layer 3 802.1Q is an 

incorrect answer because 802.1Q is used for switch trunks. Layer 3 unicasts are the form 

of communication clients use after obtaining an IP address.

 33.  B.  DHCP clients request a renewal of the lease halfway through the lease time of the 

IP address. One-quarter of the lease is an incorrect answer. Seven-eighths of the lease 

is called the rebind time, where the client will accept a new IP address from any DHCP 

server. The end of the lease is when the client must relinquish the IP address.

 34.  C.  After the initial Discover, Offer, Request, and Acknowledge, it is the client’s 

responsibility to maintain the lease of the IP address. This includes release and renewal. 

The DHCP server is not responsible for maintaining the life cycle of an IP address. DHCP 

does not use multicasting between the client and server. The DHCP lease is mandated by 

the configuration on the DHCP server.

 35.  A.  DHCP uses UDP as a connectionless protocol for the Discover, Offer, Request, and 

Acknowledge packets. ICMP is used by Ping and Traceroute to verify the response and 

path of a packet. TCP is not used by DHCP. RARP is not used by DHCP; it is considered 

an alternate method of assigning an IP address to a client.

 36.  B.  When DHCP detects a duplicate IP address in the pool, it will remove the duplicate IP 

address from the DHCP pool and place it into the conflict table. It will require manual 

intervention to reserve the IP address. The IP address is placed into a conflict table, and 

therefore, it is not served to any client. The DHCP server will continue to serve other 

available IP addresses in the DHCP pool. The duplicate IP address can only be served in 

the future if it is cleared from the conflict table.

 37.  D.  SNMP version 3 introduced message integrity, authentication, and encryption to the 

SNMP suite. SNMP version 1 was the first release of SNMP and considered deprecated. 

SNMP version 2e is not a valid version of SNMP. SNMP version 2c is an amendment  

of SNMP version 2 that added the SET command and other improvements.

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Chapter 4: IP Services (Domain 4)