ICND1 Infrastructure Services 2 — Questions and Answers
Question 1: Which DHCP message does a client send to request an IP address from a specific DHCP server after receiving multiple offers?
- DHCPDISCOVER
- DHCPREQUEST (Correct answer)
- DHCPACK
- DHCPNAK
Correct answer: DHCPREQUEST
DHCPREQUEST is broadcast by the client to select one server's offer and inform all other servers their offers were declined.
Question 2: What is the default lease time for DHCP addresses on a Cisco IOS router?
- 1 day (Correct answer)
- 8 hours
- 24 hours
- 1 hour
Correct answer: 1 day
Cisco IOS DHCP server defaults to a 1-day (86400 seconds) lease time unless configured otherwise.
Question 3: A router needs to forward DHCP broadcasts from clients on one subnet to a DHCP server on another subnet. Which command enables this?
- ip dhcp pool
- ip helper-address (Correct answer)
- ip dhcp relay
- ip forward-protocol udp 67
Correct answer: ip helper-address
The 'ip helper-address' command on the client-facing interface forwards DHCP broadcasts as unicast to the specified DHCP server.
Question 4: Which DNS record type maps an IPv4 hostname to an IP address?
- PTR
- MX
- A (Correct answer)
- AAAA
Correct answer: A
An 'A' record maps a fully qualified domain name (FQDN) to an IPv4 address.
Question 5: What well-known UDP port does NTP use?
- 161
- 123 (Correct answer)
- 69
- 514
Correct answer: 123
NTP operates on UDP port 123 to synchronize time between network devices.
Question 6: Which NTP stratum level is assigned to devices that synchronize directly from an atomic clock or GPS source?
- Stratum 0
- Stratum 1 (Correct answer)
- Stratum 2
- Stratum 15
Correct answer: Stratum 1
Stratum 1 devices synchronize directly from a Stratum 0 reference clock (atomic/GPS) and serve as primary NTP servers.
Question 7: A Cisco router is configured with 'ntp server 192.168.1.1'. What role does this router play?
- NTP master
- NTP client (Correct answer)
- NTP peer
- NTP broadcast server
Correct answer: NTP client
The 'ntp server' command configures the router as an NTP client that synchronizes its clock from the specified server.
ICND1 Infrastructure Services 2
Which DHCP message does a client send to request an IP address from a specific DHCP server after receiving multiple offers?