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CompTIA A+ 1101 > 2.6 DNS Configuration, DHCP Configuration, VLANs & VPNs > Flashcards

2.6 DNS Configuration, DHCP Configuration, VLANs & VPNs Flashcards

1
Q

Domain Name System

A
  • Translates human-readable names into computer
    -readable IP addresses
    – You only need to remember www.ProfessorMesser.com
  • Hierarchical
    – Follow the path
  • Distributed database
    – Many DNS servers
    – 13 root server clusters (over 1,000 actual servers)
    – Hundreds of generic top-level domains (gTLDs)
    -.com, .org, .net, etc.
    – Over 275 country code top-level domains (ccTLDs)
    -.us, .ca, .uk, etc.
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2
Q
  • Translates human-readable names into computer
    -readable IP addresses
    – You only need to remember www.ProfessorMesser.com
  • Hierarchical
    – Follow the path
  • Distributed database
    – Many DNS servers
    – 13 root server clusters (over 1,000 actual servers)
    – Hundreds of generic top-level domains (gTLDs)
    -.com, .org, .net, etc.
    – Over 275 country code top-level domains (ccTLDs)
    -.us, .ca, .uk, etc.
A

Domain Name System

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3
Q

DNS records

A
  • Resource Records (RR)
    – The database records of domain name services
  • Over 30 record types
    – IP addresses, certificates, host alias names, etc.
  • These are important and critical configurations
    – Make sure to check your settings, backup, and test!
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4
Q
  • Resource Records (RR)
    – The database records of domain name services
  • Over 30 record types
    – IP addresses, certificates, host alias names, etc.
  • These are important and critical configurations
    – Make sure to check your settings, backup, and test!
A

DNS records

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5
Q

Address records (A) (AAAA)

A
  • 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
  • AAAA records are for IPv6 addresses
    – The same DNS server, different records
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6
Q
  • Determines the host name for the mail server - this isn’t an IP address; it’s a name* 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
  • AAAA records are for IPv6 addresses
    – The same DNS server, different records
A

Address records (A) (AAAA)

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7
Q

Mail exchanger record (MX)

A
  • Determines the host name for the mail server
  • this isn’t an IP address; it’s a name
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8
Q
  • Determines the host name for the mail server
  • this isn’t an IP address; it’s a name
A

Mail exchanger record (MX)

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9
Q

Text records (TXT)

A
  • Human-readable text information
    – Useful public information
    – Was originally designed for
    informal information
  • Can be used for verification purposes
    – If you have access to the DNS,
    then you must be the administrator of the domain name
  • Commonly used for email security
    – External email servers validate
    information from your DNS
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10
Q
  • Human-readable text information
    – Useful public information
    – Was originally designed for
    informal information
  • Can be used for verification purposes
    – If you have access to the DNS,
    then you must be the administrator of the domain name
  • Commonly used for email security
    – External email servers validate
    information from your DNS
A

Text records (TXT)

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11
Q

Domain Keys Identified Mail (DKIM)

A
  • Digitally sign a domain’s outgoing mail
    – Validated by mail servers, not usually
    seen by the end user
    – The public key is in the DKIM TXT record
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12
Q
  • Digitally sign a domain’s outgoing mail
    – Validated by mail servers, not usually
    seen by the end user
    – The public key is in the DKIM TXT record
A

Domain Keys Identified Mail (DKIM)

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13
Q

DMARC

A
  • Domain-based Message Authentication, Reporting, and Conformance (DMARC)
    – Prevent unauthorized email use (spoofing)
    – An extension of SPF and DKIM
  • You decide what external email servers should do with emails that don’t validate through SPF or DKIM
    – That policy is written into a DMARC TXT record
    – Accept all, send to spam, or reject the email
    ; DKIM TXT records
    – Compliance reports can be sent to the email administrator
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14
Q
  • Domain-based Message Authentication, Reporting, and Conformance (DMARC)
    – Prevent unauthorized email use (spoofing)
    – An extension of SPF and DKIM
  • You decide what external email servers should do with emails that don’t validate through SPF or DKIM
    – That policy is written into a DMARC TXT record
    – Accept all, send to spam, or reject the email
    ; DKIM TXT records
    – Compliance reports can be sent to the email administrator
A

DMARC

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15
Q

Sender Policy Framework (SPF)

A
  • SPF protocol
    – A list of all servers authorized to send emails
    for this domain
    – Prevent mail spoofing
    – Mail servers perform a check to see if incoming mail
    really did come from an authorized host
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16
Q
  • SPF protocol
    – A list of all servers authorized to send emails
    for this domain
    – Prevent mail spoofing
    – Mail servers perform a check to see if incoming mail
    really did come from an authorized host
A

Sender Policy Framework (SPF)

17
Q

Scope properties

A
  • IP address range
    – And excluded addresses
  • Subnet mask
  • Lease durations
  • Other scope options
    – DNS server
    – Default gateway
    – VOIP servers
18
Q
  • IP address range
    – And excluded addresses
  • Subnet mask
  • Lease durations
  • Other scope options
    – DNS server
    – Default gateway
    – VOIP servers
A

Scope properties

19
Q

DHCP pools

A
  • Grouping of IP addresses
    – Each subnet has its own scope
    – 192.168.1.0/24
    – 192.168.2.0/24
    – 192.168.3.0/24
    – …
  • A scope is generally a single contiguous
    pool of IP addresses
    – DHCP exceptions can be made inside of the scope
20
Q
  • Grouping of IP addresses
    – Each subnet has its own scope
    – 192.168.1.0/24
    – 192.168.2.0/24
    – 192.168.3.0/24
    – …
  • A scope is generally a single contiguous
    pool of IP addresses
    – DHCP exceptions can be made inside of the scope
A

DHCP pools

21
Q

DHCP address assignment

A
  • Dynamic assignment
    – DHCP server has a big pool of addresses to give out
    – Addresses are reclaimed after a lease period
  • Automatic assignment
    – Similar to dynamic allocation
    – DHCP server keeps a list of past assignments
    – You’ll always get the same IP address
22
Q
  • Dynamic assignment
    – DHCP server has a big pool of addresses to give out
    – Addresses are reclaimed after a lease period
  • Automatic assignment
    – Similar to dynamic allocation
    – DHCP server keeps a list of past assignments
    – You’ll always get the same IP address
A

DHCP address assignment

23
Q

DHCP address allocation

A
  • Address reservation
    – Administratively configured
  • Table of MAC addresses
    – Each MAC address has a matching IP address
  • Other names
    – Static DHCP Assignment, Static DHCP,
    Static Assignment, IP Reservation
24
Q
  • Address reservation
    – Administratively configured
  • Table of MAC addresses
    – Each MAC address has a matching IP address
  • Other names
    – Static DHCP Assignment, Static DHCP,
    Static Assignment, IP Reservation
A

DHCP address allocation

25
Q

DHCP leases

A
  • Leasing your address
    – It’s only temporary
    – But it can seem permanent
  • Allocation
    – Assigned a lease time by the DHCP server
    – Administratively configured
  • Reallocation
    – Reboot your computer – Confirms the lease
  • Workstation can also manually release the IP address
    – Moving to another subnet
26
Q
  • Leasing your address
    – It’s only temporary
    – But it can seem permanent
  • Allocation
    – Assigned a lease time by the DHCP server
    – Administratively configured
  • Reallocation
    – Reboot your computer
    – Confirms the lease
  • Workstation can also manually release the IP address
    – Moving to another subnet
A

DHCP leases

27
Q

DHCP renewal

A
  • T1 timer
    – Check in with the lending DHCP server to renew the IP address
    – 50% of the lease time (by default)
    T2 timer
    – If the original DHCP server is down, try rebinding
    with any DHCP server
    – 87.5% of the lease time (7/8ths)
28
Q

LANs

A
  • Local Area Networks
  • A group of devices in the same broadcast domain
29
Q

Virtual LANs

A
  • Virtual Local Area Networks
  • A group of devices in the same broadcast domain
  • Separated logically instead of physically
30
Q
  • Virtual Local Area Networks
  • A group of devices in the same broadcast domain
  • Separated logically instead of physically
A

Virtual LANs

31
Q
  • Local Area Networks
  • A group of devices in the same broadcast domain
A

LANs

32
Q

Configuring VLANs

A
  • Virtual Local Area Networks
    – A group of devices in
    the same broadcast domain
33
Q
  • Virtual Local Area Networks
    – A group of devices in
    the same broadcast domain
A

Configuring VLANs

34
Q

VPNs

A
  • Virtual Private Networks
    – Encrypted (private) data traversing a public network
  • Concentrator
    – Encryption/decryption access device
    – Often integrated into a firewall
  • Many deployment options
    – Specialized cryptographic hardware
    – Software-based options available
35
Q
  • Virtual Private Networks
    – Encrypted (private) data traversing a public network
  • Concentrator
    – Encryption/decryption access device
    – Often integrated into a firewall
  • Many deployment options
    – Specialized cryptographic hardware
    – Software-based options available
  • Used with client software
    – Sometimes built into the OS
A

VPNs

36
Q
  • Virtual Private Networks
    – Encrypted (private) data traversing a public network
  • Concentrator
    – Encryption/decryption access device
    – Often integrated into a firewall
  • Many deployment options
    – Specialized cryptographic hardware
    – Software-based options available
  • Used with client software
    – Sometimes built into the OS
A

VPNs

37
Q

Client-to-Site VPNs

A
  • On-demand access from a remote device
    – Software connects to a VPN concentrator
  • Some software can be configured as always-on
38
Q
  • On-demand access from a remote device
    – Software connects to a VPN concentrator
  • Some software can be configured as always-on
A

Client-to-Site VPNs

CompTIA A+ 1101 (10 decks)

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