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
• save money and energy
  Ex. One switch can be split into multiple separate VLANs (networks) instead of having a switch for each network

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