1.8 Explain the functions of network services.

Question 1

An Overview of DNS

Answer 1

• Translates human-readable names into computer-readable IP addresses

Question 2

FQDN

Answer 2

(Fully Qualified Domain Name)

Question 3

The DNS Resolution Process

Answer 3

1 - Request sent to local name server
2 - Name server queries root server
3 - Root response sent to local name server
4 - Name server queries .com name server
5 - .com Response sent to local name server
6 - Name server queries specific domain server
7 - Domain server responds to name server
8 - Name server provides result to local device
9 - Answer is cached locally

Question 4

Internal DNS

Answer 4

Managed on internal servers
• Contains DNS information about internal devices
• DNS service on Windows Server

Question 5

External DNS

Answer 5

• Does not have internal device information

* Google DNS, Quad9

Question 6

Resource Records (RR)

Answer 6

• The database records of domain name services

Question 7

Address Records (A) (AAAA)

Answer 7

• Defines the IP address of a host• This is the most popular query
• A records are for IPv4 addresses
• Modify the A record to change the host name to IP address resolution

Question 8

• AAAA records are for IPv6 addresses

Answer 8

• The same DNS server, different records

Question 9

Canonical name records (CNAME)

Answer 9

• A name is an alias of another, canonical name

Question 10

Service records (SRV)

Answer 10

• Find a specific service

* Where is the Windows Domain Controller? Where is the instant messaging server? Where is the VoIP controller?

Question 11

Mail exchanger record (MX)

Answer 11

• Determines the host name for the mail server - this isn’t an IP address; it’s a name

Question 12

Name server records (NS)

Answer 12

• List the name servers for a domain - NS records point to the name of the server

Question 13

Pointer record (PTR)

Answer 13

• The reverse of an A or AAAA record

Question 14

Text records (TXT)

Answer 14

• Human-readable text information
• SPF protocol (Sender Policy Framework)
• DKIM (Domain Keys Identified Mail) - • Digitally sign your outgoing mail

Question 15

Managing DHCP in the enterprise

Answer 15

• Limited Communication range
• Multiple servers needed for redundancy
• Send DHCP request across broadcast domains

Question 16

IP Address Management (IPAM)

Answer 16

• Manage IP addressing
• Control DHCP reservations
• Manage IPv4 and IPv6
• Report on IP address usage

Question 17

Scope properties

Answer 17

• IP address range• Subnet mask• Lease durations

* DNS server, default gateway, WINS server

Question 18

DHCP pools

Answer 18

• Grouping of IP addresses
• Each subnet has its own scope
• A scope is generally a single contiguous pool of IP addresses

Question 19

DHCP address allocation

Answer 19

• T1 timer
• Check in with the lending DHCP server to renew the IP address

• 50% of the lease time (by default)

Question 20

DHCP address allocation

Answer 20

• Dynamic allocation• Automatic allocation

* Static allocation - Each MAC address has a matching IP address

Question 21

NTP (Network Time Protocol)

Answer 21

• Switches, routers, firewalls, servers, workstations
• Synchronizing the clocks becomes critical
• Automatic updates

Question 22

NTP clients and servers

Answer 22

• Requests time updates from NTP server

Question 23

• NTP client/server

Answer 23

• Requests time updates from an NTP server

* Requests time updates from an NTP server

Question 24

NTP stratum layers

Answer 24

• Some clocks are better than others

Question 25

Configuring NTP

Answer 25

• Specify the NTP server address (IP or hostname)

* Use multiple NTP servers (if available) for redundancy