ICND1 Infrastructure Services 4 — Questions and Answers
Question 1: Which command verifies the current DHCP bindings (leases) on a Cisco IOS DHCP server?
- show ip dhcp pool
- show ip dhcp binding (Correct answer)
- show ip dhcp conflict
- show dhcp lease
Correct answer: show ip dhcp binding
'show ip dhcp binding' displays all current IP-to-MAC address mappings issued by the Cisco IOS DHCP server.
Question 2: A host receives a 169.254.x.x address. What does this indicate?
- The host is configured with a static IP
- DHCP discovery succeeded but the server is overloaded
- The host failed to receive a DHCP lease and assigned itself an APIPA address (Correct answer)
- The default gateway is unreachable
Correct answer: The host failed to receive a DHCP lease and assigned itself an APIPA address
169.254.0.0/16 is the APIPA (Automatic Private IP Addressing) range used when a DHCP client cannot reach a server.
Question 3: Which command on a Cisco router excludes the addresses 192.168.1.1 through 192.168.1.10 from being assigned by DHCP?
- ip dhcp excluded-address 192.168.1.1 192.168.1.10 (Correct answer)
- ip dhcp pool exclude 192.168.1.1 192.168.1.10
- no ip dhcp address 192.168.1.1 192.168.1.10
- ip dhcp reserve 192.168.1.1 192.168.1.10
Correct answer: ip dhcp excluded-address 192.168.1.1 192.168.1.10
'ip dhcp excluded-address' prevents the DHCP server from leasing the specified address range to clients.
Question 4: What type of DNS query does a client send when it wants the DNS server to perform all recursive lookups on its behalf?
- Iterative query
- Recursive query (Correct answer)
- Inverse query
- Authoritative query
Correct answer: Recursive query
A recursive query asks the DNS server to fully resolve the name and return the final answer, performing all necessary additional queries itself.
Question 5: Which command configures a Cisco router to use 8.8.8.8 as its DNS server?
- ip name-server 8.8.8.8 (Correct answer)
- ip dns-server 8.8.8.8
- ip domain-lookup 8.8.8.8
- ip host dns 8.8.8.8
Correct answer: ip name-server 8.8.8.8
'ip name-server' specifies the DNS server(s) that the router will use for hostname resolution.
Question 6: A Cisco router has 'no ip domain-lookup' configured. What is the effect?
- DNS lookups are sent to the broadcast address
- The router cannot ping any host by IP address
- Mistyped commands are not sent as DNS queries, preventing long delays (Correct answer)
- The router uses only local hosts entries
Correct answer: Mistyped commands are not sent as DNS queries, preventing long delays
'no ip domain-lookup' disables DNS resolution on the router, preventing mistyped CLI commands from being broadcast as DNS queries and causing delays.
Question 7: Which protocol allows a network device to obtain an IP address, subnet mask, default gateway, and DNS server from a single server automatically?
- ARP
- DHCP (Correct answer)
- RARP
- BOOTP
Correct answer: DHCP
DHCP (Dynamic Host Configuration Protocol) automatically provides clients with IP address, subnet mask, gateway, DNS, and other parameters.
ICND1 Infrastructure Services 4
Which command verifies the current DHCP bindings (leases) on a Cisco IOS DHCP server?