2.6 Common Network Configuration

Question 1

DNS Hierarchy

Answer 1

1. Root servers at the top
2. Top Level Domain (TLD) Server
   - .com, .org, .net, etc
   Country Code TLD Server
   - .us, .ca, etc
3. Servers for specific domains

Question 2

Address Records: A vs AAAA

Answer 2

Defines the IP address of a domain
(A) records are for IPv4 addresses
(AAAA) records are for IPv6 addresses

Question 3

Mail Exchange (MX) Record

Answer 3

Specifies the mail server responsible for accepting email messages on behalf of a domain name

Question 4

Text (TXT) Records

Answer 4

• DNS record in text format
• Contains information about your domain
• can be used for verification
• spam management: SPF, DKIM, DMARC

Question 5

Domain Keys Identified Mail (DKIM)

Answer 5

• Sender can digitally sign and authenticate outgoing mail
• used to identify an authorized sender for a particular domain name

Question 6

Sender Policy Framework (SPF)

Answer 6

A list of all servers authorized to send emails for this domain. Mail servers check to see if incoming mail came from an authorized host.

Question 7

Domain-Based Message Authentication, Reporting, and Comformance (DMARC)

Answer 7

Domain owners decide what external email servers should do with emails that don’t validate through DKIM or SPF. The policy is written into a DMARC TXT record.

Question 8

DHCP Scope

Answer 8

Defines the parameters of a DHCP server such as:
IP address range
Subnet mask
Lease duration
DNS server settings
Default gateway
VOIP servers

Question 9

DHCP Dynamic vs Automatic Assignment

Answer 9

Dynamic:
- assign address from DHCP pool
- address reclaimed after lease period
Automatic:
- DHCP server keeps list of past assignments
- devices are assigned the same IP if still available

Question 10

DHCP Leases

Answer 10

• temporary IP address assignment
• address is reclaimed after lease period
• lease period is administratively configured

Question 11

DHCP Reservation

Answer 11

• assign a specific IP address to a device based on MAC address
• IP address is always assigned to the same device when connected to the network

Question 12

VLAN

Answer 12

• a group of devices in the same broadcast domain across the same physical device
  Ex. One switch can be split into multiple separate VLANs

Question 13

VPN

Answer 13

Virtual Private Network
- sends encrypted data across a public network
- usually a combination of software and hardware
- many VPNs are now software based