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CompTIA A+ 1101 (Core 1)_ > 2.6 Compare & contrast common network configuratoin concepts > Flashcards

2.6 Compare & contrast common network configuratoin concepts Flashcards

1
Q

What is a DHCP scope?

A

DHCP server’s address range for subnet clients

A scope of 192.168.0.100 - 192.168.0.199 allows for 100 dynamically addressed hosts on the LAN

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2
Q

What addresses should the DHCP scope exclude?

A

Addresses that have been configured statically

i.e. if you’ve manually assigned the IP address 192.168.1.10 to a printer, you would want to exclude this address from the DHCP scope to prevent the DHCP server from assigning it to another device.

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3
Q

How is a host configured to use DHCP?

A

By setting its TCP/IP config. to automatically obtain an IP address

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4
Q

What happens when a DHCP client connects to a network?

A

It broadcasts a DHCPDISCOVER packet to find a DHCP server

Since clients BROADCAST this packet, meaning they send it to all devices on the network, they do not need to know the DHCP server’s IP address

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5
Q

Why do DHCP servers need to have a static IP address?

A

To ensure DHCP clients reliably find the server for IP assignment or renewal

If the DHCP server’s IP address were to change frequently, DHCP clients wouldn’t be able to reliably locate it to obtain network configuration information.

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6
Q

What does the DHCP server do when it receives a DHCPDISCOVER packet?

A

Responds with a DHCPOFFER packet

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7
Q

What does a DHCPOFFER packet contain?

A

Address & other configuration data

other config data like the default gateway & DNS server addresses

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8
Q

What does the DHCP client do when it receives a DHCPOFFER packet?

A

Broadcasts a DHCPREQUEST onto the network

it broadcasts the packet to inform all DHCP servers on the network that the client has accespted the IP address offer provided by one of the servers

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9
Q

What happens after a DHCPREQUEST packet is broacasted onto the network?

A

Server responds with a DHCPACK packet

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10
Q

What happens when the client receives a DHCPACK packet?

A

Client broadcasts an ARP message to check that the address is unused

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11
Q

Meaning of ARP?

A

Address Resolution Protocol

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12
Q

What if a client detects an IP address conflict after sending an ARP message?

Meaning the client detecs a duplicate IP after sending ARP message

A

It declines the IP address offer & requests a new one

If it detects that it isnt used, then it proceeds to use it.

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13
Q

What can a client do to retain an IP address before the lease ends?

A

Attempt to renew or rebind the lease

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14
Q

What if a client can’t renew/rebind its IP address lease?

A

Must release the IP address & start the discovery process again

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15
Q

How can a client’s network configuration be changed?

i.e. assiging different IP addresses or adjusting other settings

A

Manually or via DHCP server

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16
Q

When do DHCP updates to a client’s network settings take effect?

A

When DHCP client seeks a new lease

A new lease can also be requested manually

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17
Q

What happens in a DHCP reservation?

A

DHCP server reserves an IP address for a device

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18
Q

How does a DHCP server identify the device for a reserved address?

Meaning how does it know which device to assign the reserved address

A

Using a list of hosts’ MAC addresses for IP assignment

When contacted by a listed host, it issues a lease for reserved IP

Some OSs send a different unique identifier instead of MAC addresses by default. Configuring the identification method ensures accurate server info.

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19
Q

What is a hostname?

A

Label assigned to a device on a network

It serves as a human-readable identifier for the device

i.e. computer01.local

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20
Q

How is the possibility of duplicate hostnames on the Internet avoided?

A

Having the hostname combined with a domain name & suffix

“web1” + “example.com” becomes “web1.example.com,” avoiding duplicates

Note that, while combining the hostname with a domain name and suffix helps, it’s part of a broader set of measures used to avoid duplicate hostnames on the Internet. (i.e. Domain registration, Reverse DNS lookup, etc.)

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21
Q

Meaning of FQDN?

A

Fully Qualified Domain Name

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22
Q

What is a FQDN?

A

Hostname combined with a domain name & suffix

i.e. nut.widget.examplle

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23
Q

Identify hostname of this FQDN:

nut.widget.example

A

nut

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24
Q

Identify domain name of this FQDN:

nut.widget.example

A

widget

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25
Q

Identify the TLD (domain suffix) of this FQDN:

nut.widget.example

A

.example

A domain suffix could also contain subdomains between the host & domain name

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26
Q

Meaning of TLD?

A

Top-Level Domain

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27
Q

How are FQDNs assigned & managed?

A

Using DNS

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28
Q

What is DNS?

A

Global hierarchy of distributed databases with domain & host info.

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29
Q

What is at the top of the DNS hierarchy?

A

Root

Root is represented by a null label, consisting of just a (.)

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30
Q

How many root servers does the DNS hierarchy have?

A

13 root-level servers

(A to M)

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31
Q

What is below the root in the DNS hierarchy?

A

TLDs

The most prevalent are genereic (i.e. .com, .org, .net, .info, .biz), sponsored (i.e. .gov, .edu), & country code (i.e. .uk, .ca, .de)

32
Q

What does a client need to resolve a hostname/FQDN to an IP address?

A

The appropriate DNS record from a DNS server

33
Q

What must atleast one DNS server be configured as in a network?

A

Configured as an authoritative store for domain info.

Authoritative DNS records contain numerous resource records

This means that there should be at least one DNS server configured to hold the official DNS records for each domain in that network

34
Q

What do DNS resource records allow the DNS server to do?

A

Resolve domain names & services into IP addresses

35
Q

What is an Address record (A) used for?

A

Resolving a host name to an IPv4 address

36
Q

What is an AAAA record used for?

A

Resolving a host name to an IPv6 address

37
Q

Meaning of MX?

A

Mail eXchanger

38
Q

What are MX records used for?

A

Identify domain’s email server for message delivery

39
Q

What do preference values in MX records indiate?

A

Priority order for handling incoming email

Preference values in MX records indicate the priority of email servers. Lower values have higher priority, so email is routed to the server with the lowest preference value first

40
Q

What does the hostname with an MX record need?

A

Associated A or AAAA record

41
Q

What are TXT records used for?

A

Storing text for supporting network services

42
Q

2 main reasons domain names have TXT records?

A
  • Verify email services
  • Block spam

Spam is spoofed & unwatned messages

43
Q

Meaning of SPF?

A

Sender Policy Framework

44
Q

How is SPF record implemented as?

A

TXT resource record in DNS

45
Q

How many SPF records should each domain have?

A

1

46
Q

What does SPF identify?

A

Email servers allowed to send emails for a domain

SPF checks if a sending mail server is authorized to send emails for a domain by querying its DNS records. i.e. if example.com has an SPF record specifying certain IP addresses, only those addresses can send emails as @example.com, helping to prevent spoofing and spam.

47
Q

What does SPF do?

A
  • Identifies authorized hosts
  • Handles unauthorized servers
48
Q

3 things SPF can do to emails from servers not on the list?

A
  • Accept
  • Flag
  • Reject
49
Q

Syntax used in SPF to accept emails from servers not listed?

A

+all

50
Q

Syntax used in SPF to flag emails from servers not listed?

A

~all

51
Q

Syntax used in SPF to reject emails from servers not listed?

A

-all

52
Q

Meaning of DKIM?

A

DomainKeys Identified Mail

53
Q

3 DNS spam management records?

A
  • SPF
  • DKIM
  • DMARC

These are TXT records

54
Q

What does DKIM do?

A

Uses crpytography to validate the email’s source server

The sender’s server creates a unique digital signature by hashing specific email content and encrypting it with the sender’s private key. The recipient’s server then retrieves and verifies the DKIM signature using the sender’s public key from DNS records. If successful, it confirms the email’s origin and integrity; otherwise, it flags potential tampering for further review.

55
Q

Does DKIM replace or supplement SPF?

A

Either or

It can do either one

56
Q

How is DKIM configured?

A

Uploading a public encryption key as a TXT record in the DNS server

Orgs. receiving messages can use this key to verify that a message derives from an authentic server

57
Q

Meaning of DMARC?

A

Domain-based Message Authentication, Reporting, & Conformance

58
Q

What does DMARC framework do?

A

Ensures SPF & DKIM are being utilized effectively

59
Q

How are DMARC policies published as?

A

DNS TXT record

60
Q

Which DNS spam management records can DAMRC use?

A

SPF or DKIM or both

61
Q

What does DMARC allow?

A
  • Senders define DMARC authenticaiton failure handling
  • Recipients to report failures to senders
62
Q

3 ways DMARC authentication failures can be treated?

A
  • Flag
  • Quarantine
  • Reject
63
Q

What type of switches support VLANs?

A

Managed switches

64
Q

Meaning of VLAN?

A

Virtual LAN

65
Q

What does VLAN do to managed switches?

A

Divides the ports into groups

66
Q

Simplest way of assigning a node to a VLAN?

A

Configure switch port with a VLAN ID of 2 to 4049

i.e. Switch ports 1-10 could be VLAN 10, and ports 11-20 VLAN 20. Host A on port 2 is in VLAN 10, and host B on port 12 is in VLAN 20.

67
Q

What is VLAN ID 1 referred to?

A

default VLAN

68
Q

What VLAN ID do ports on a managed switch default to?

A

VLAN ID 1

Unless configured differently

69
Q

What happens when hosts are placed in separate VLANs?

A

They can’t directly communicate with each other

Even though they are on the same managed switch

70
Q

What must each VLAN be configured with?

A

Its own subnet address & IP address range

71
Q

How are communications between VLANs done?

A

Via IP router

Each VLAN must also be provisioned with its own DHCP & DNS services

72
Q

Benefits of VLAN?

A
  • Reduces broadcast traffic impact
  • Eases traffic filtering & monitoring

VLANs are also used to separate nodes by traffic type, like isolating VoIP devices for easier prioritization over other VLANs.

73
Q

Meaning of VPN?

A

Virtual Private Network

74
Q

What do VPNs do?

A

Allows hosts to remotely connect to the LAN

75
Q

How does a host connect to a LAN with a VPN?

A

Via a remote access server accepting connections from the Internet

Because the Internet is a public network, ensure the VPN connection is secure

76
Q

What do secure VPNs configure?

A

A protected tunnel through the Internet

It employs specialized connection protocols and encryption to safeguard the tunnel from snooping and ensure proper user authentication.

77
Q

Another way VPNs can be used?

A

Securely connect sites over public or local networks

For added security

A company securely links its branch offices over the internet using VPNs. This allows employees to access shared resources as if they were on the same local network, while encryption ensures data security during transmission.

CompTIA A+ 1101 (Core 1)_ (28 decks)

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