Day 23 - DHCP & DNS

Question 1

When a DHCPv4-configured device boots up or connects to the network, the client broadcasts what type of message?

Answer 1

DHCPDISCOVER broadcast message

Question 2

After a DHCP client sends a DHCPDISCOVER broadcast message, what does the DHCP server respond with?

Answer 2

DHCPOFFER unicast message

Question 3

After a DHCP server sends a DHCPOFFER unicast message, what does the DHCP client respond with?

Answer 3

DHCPREQUEST broadcast message

Question 4

After the DHCP client sends the DHCPREQUEST broadcast message, what does the DHCP server respond with?

Answer 4

DHCPACK

Question 5

If a client is powered down or taken off the network, the IP address given by DHCP is what?

Answer 5

Returned to the pool for reuse

Question 6

In what ways can a Cisco router be involved with DHCP

Answer 6

As a DHCP server
A DHCP relay agent
A DHCP client

Question 7

What are the commands to configure a Cisco DHCP server to hand out ip addresses?

Answer 7

ip dhcp excluded-address {starting-ip-address} {ending-ip-address}
ip dhcp pool {name-of-pool}
network {network-address} {subnet}
default-router {ip-address}
dns-server {ip-address}

Question 8

What command would you check to see if DHCP for a Router is being used a DHCP client?

Answer 8

show dhcp lease

Question 9

What commands would you use on a Router to set it up as a DHCP client?

Answer 9

int {int}
-outside facing interface to the ISP
ip address dhcp
no shutdown

Question 10

What command would you use to disable DHCP service on a device?

Answer 10

no service dhcp

Question 11

What command would you use to verify DHCPv4 operation?

Answer 11

show ip dhcp binding

Question 12

On a DHCP client, how would you release and renew DHCP configurations?

Answer 12

ipconfig /release
ipconfig /renew

Question 13

To ensure that broadcasted DHCPDISCOVER messages are sent to the remote DHCPv4 server, what command would you use on a Cisco device?

Answer 13

ip helper-address

Question 14

How many UDP services does the ip helper-address command forward?

Answer 14

8

Question 15

What services does the ip helper-address command forward?

Answer 15

Port 37: Time
Port 49: TACACS
Port 53: DNS
Port 67: DHCP/BOOTP Server
Port 68: DHCP/BOOTP Client
Port 69: TFTP
Port 137: NetBios name service
Port 138: NetBios datagram service

Question 16

How would you specify additional protocols other than DHCP to be forwarded by the ip helper-address command?

Answer 16

ip forward-protocol udp {port-number} {protocol}

Question 17

IPv6 has two methods for obtaining a global unicast address. What are they?

Answer 17

SLAAC (Stateless address autoconfiguration)
Stateful DHCPv6

Question 18

This method of obtaining an IPv6 address uses ICMPv6 Router Solicitation and Router Advertisement messages to provide addressing and other configuration information

Answer 18

SLAAC

Question 19

When a client is configured to obtain its addressing information automatically using SLAAC, the client sends a __________ __________ __________ to the router. This message is then sent to the IPv6 all-routers __________ __________

Answer 19

Router Solicitation message
Multicast address

Question 20

An IPv6 DHCP client uses this type of Neighbor Discovery protocol message to create its own IP address

Answer 20

Router advertisement (RA)

Question 21

This type of message is normally used to learn the data link layer address of a neighbor on the same network

Answer 21

Neighbor Solicitation message

Question 22

What type of message informs a client how to obtain automatic IPv6 addressing?

Answer 22

Router Advertisement message

Question 23

To configure a router as a stateless DHCP server, you need to make sure what is enabled?

Answer 23

ipv6 unicast-routing

Question 24

What are some types of record address for DNS?

Answer 24

A
NS
AAAA
MX

Question 25

What does URI stand for?

Answer 25

Uniform resource identifier

Question 26

What command would you use on a MacOS or Linux client to verify network information such as gateway address, IP address, etc.

Answer 26

ifconfig

Question 27

With IPv6 SLAAC, routers respond to RS messages with what?

Answer 27

Router advertisements