1.8 DHCP/DNS services

Question 1

How does a DHCP reservation work?

Answer 1

When the client requests an IP address by sending a message to the DHCP server, the server will assign an IP from its DHCP scope and reserve it based on its MAC address.
It will match IP addresses to a specified MAC address.

Question 2

What is a DHCP relay?

Answer 2

It is used to forward/proxy client requests for IP configurations across different physical subnets.

Question 3

DNS is considered to be a heirarchal system, why?

Answer 3

DNS follows a specific path across a distributed database to locate the record assocaited with your query.
A query gets redirected from a root server to gTLD servers or ccTLD servers based on the URL presented.

Question 4

What is a FQDN?

Answer 4

Fully Qualified Domain Name; It is a completely specified domain name that includes the top-level domain. Represents a web, mail, or file server.

(www.google.com -> google.com is the FQDN)

Question 5

What is a URL?

Answer 5

Uniform Resource Locator;
An address that combines domain name and filepath syntax.
Contains the FQDN with method of accessing information.

(Https:// being a method of access.)

Question 6

What is an internal DNS?

Answer 6

A DNS server maintained by and for exclusive use by an organization for internal devices.

Question 7

What is an external DNS?

Answer 7

A DNS service provided for the public that does not have internal device information.

Question 8

What is 3rd party/cloud-hosted DNS? What is its benefit?

Answer 8

DNS services meant to be used internally within an organization, but is maintained by a 3rd party.
They are highly scaleable for large businsesses or organizations that have services around the world.

Question 9

What is an A record?

Answer 9

Address record;
Name to IP address.
It defines the IPv4 address of a host/FQDN.

Question 10

What is an AAAA record?

Answer 10

Address record;
Name to IP address.
It defines the IPv6 address of a host/FQDN.

Question 11

What is a TXT record?

Answer 11

Text;
Does not have to point to other records.
Holds human or machine readible information such as SPF, DKIM, or encryption rules.

Question 12

What is an SRV record?

Answer 12

Service;
Name to A record.
A newer record that defines how to access a general service, does not need to be specific about the service like MX or CNAME.

Also defines the port number and target device.

For example, can specificy the VoIP controller, SMS server, or Windows domain controller (LDAP).

Question 13

What is an CNAME record?

Answer 13

Canonical name;
Name to A record or another CNAME record.

Associates aliases (canonical names) with an existing A/AAAA record (primary name).

Question 14

What is an NS record?

Answer 14

Name Server;
Name to A record.

Specifies the authoratative name server for a domain.

Question 15

What is an PTR record?

Answer 15

Pointer;

reverse of A/AAAA record. Resolves an IP address into an FQDN.

Question 16

What is an MX record?

Answer 16

Mail Exchange;
Name to A record.

Determines the domain/host name for an email server.

Question 17

What is the forward zone?

Answer 17

Forward lookup zones resolve names to IP addresses.

contains A/AAAA records

Question 18

What is the reverse zone?

Answer 18

Reverse lookup zones resolve IP addresses to names. (contains PTR records).

Question 19

What is used to comment DNS records?

Answer 19

;

Question 20

What is used to comment DNS records?

Answer 20

;

Question 21

What is SPF?

Answer 21

Sender Policy framework;

A TXT record that prevents incoming mail spoofing by checking for authenticity of origin.

Question 22

What is DKIM?

Answer 22

Domain Keys Identified Mail;
Digitally signs outgoing mail.
Puts public key in DNS record to allow other mail servers to veryfy mail really came from you.

Question 23

What is DKIM?

Answer 23

Domain Keys Identified Mail;
Digitally signs outgoing mail.
Puts public key in DNS record to allow other mail servers to verify mail really came from you.

Question 24

What is the most accurate NTP server called when configuring NTP clients?

Answer 24

Stratum 0

Question 25

What information is needed when configuring NTP?

Answer 25

IP or hostname of NTP server(s), stratum level

Question 26

What does the DHCP scope define?

Answer 26

Address pool, IP reservations, lease times, subnet masks, default gateway, DNS server, WINS server.

Question 27

Each subnet should have its own DHCP ___ and ___.

Answer 27

scope and pool.

Question 28

What is dynamic allocation?

Answer 28

DHCP server gives random IP address each time to a joining device.

Question 29

What is automatic allocation?

Answer 29

The DHCP server permanently assigns a static IP address to a particular device. The only way to change it is to manually reconfigure the device.

Question 30

What is static DHCP?

Answer 30

A device will always have the same reserved IP address.

Question 31

What are the 4 steps of DHCP?

Answer 31

Discover broadcast sent from client
Offer broadcast sent from server
Request broadcast sent from client
Acknowledgement broadcast sent from server

Question 32

DHCP server uses what port?

Answer 32

UDP/67

Question 33

What port does a DHCP client use?

Answer 33

UDP/68

Question 34

What is IPAM?

Answer 34

IP address management;

tools that manage and monitor IP addressing, scope options, DHCP statistics, reservations etc for one or more servers.