DNS Flashcards

1
Q

Define Root Domain

A

Top level of the DNS namespace hierarchy

Defined by a .

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2
Q

What are the queries a DNS client can make to a DNS server

A

Recursive
Iterative
Reverse lookup

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3
Q

Examples of Top Level Domains

A

.com .edu .gov .us .ca .biz .info

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4
Q

What are Second Level Domains

A

below TLD

limit of 127 subdomains under second level domains

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5
Q

Max length of FQDN

A

255 char

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6
Q

Define FQDN

A

Fully qualified domain name

Composed of hostname, an organization’s domain name and the Internet top-level domain name

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7
Q

What are the types of DNS queries

A

Recursive
Iterative
Reverse Lookup

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8
Q

What are Recursive queries

A

Name server receiving this query must respond with IP for a name or an error stating data of requested type doesn’t exist or domain name specified doesn’t exist

Name server cannot refer client to another name server. It will send iterative queries out to other names servers until the answer is found or return error if none exists

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9
Q

What is an Iterative query

A

Name server provides best answer it has whether its the answer or another name server that may know

Clients cannot make iterative queries

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10
Q

What is a DNS Zone

A

A contiguous portion of a DNS namespace managed by one or more servers

Zones defined by who looks after maintaining the records that they contain

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11
Q

What are Reverse Lookup Queries

A

client sends IP address to DNS server and it responds with hostname

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12
Q

What domain is used with reverse lookup queries

A

in-addr.arpa for IPv4

IP6.ARPA for IPv6

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13
Q

How should an IP in a reverse lookup query be written

A

In reverse

Domain names become more specific right to left while IP address become more specific left to right

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14
Q

What does the ICANN/IANA do

A

Keep database that contains names of registered domains and DNS servers that server these domains

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15
Q

What is a HOSTS file

A

Flat database that contains static mappings for IP addresses to domain names

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16
Q

What does a top level domain need from a company to register an Internet domain name

A

IP of at least two DNS servers that are authoritative for that domain

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17
Q

Why do many organizations limit host names to 15 characters

A

NetBIOS names are derived from first 15 characters of the hostnmae

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18
Q

What are root servers

A

The 13 DNS server names in the root domain managed by ICANN

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19
Q

What are the ways to install DNS

A

Add Roles and Features
Can be installed when installing AD DS
With Powershell

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20
Q

How to install DNS using Powershell

A

Add-WindowsFeature DNS

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21
Q

How to install DNS and AD DS using powershell

A
Add-WindowsFeature AD-Domain-Services
Import-module ADDSDeployment
Install-ADDSDomainController -InstallDns -DomainName "corp.contoso.com "
22
Q

What is an Authoritative Server

A

DNS server that is main source of information regarding the IP addresses contained within a zone

23
Q

What is a zone transfer

A

Replication between DNS servers

24
Q

What are the different types of Zones

A
Primary
Secondary
Stub
Active Directory Integrated
GlobalNames
25
Q

What is a Primary Zone

A

Master copy of zone data hosted on a DNS server that is the primary source of info for records found in this zone

26
Q

What is a Master Server

A

DNS server that is authoritative for a zone and is able to directly update zone data
Hosts the primary zone data

27
Q

Where is the zone data stored

A

On the master server in %systemroot%\system32\DNS\zone\name.dns

Stored here only if zone data is not integrated with AD DS

28
Q

What is a Secondary Zone

A

Additional copy of the DNS zone data hosted on a DNS server that is a secondary source for this zone information

Used for redundancy and load balancing

29
Q

What is a Secondary Server

A

DNS server that hosts the secondary zone

Obtains zone information from the Master server in the corresponding primary zone

DNS server can host multiple zone files that can be a mixture of primary and secondary zones

Secondary zone can act as a master zone for another secondary zone

30
Q

What is a Stub Zone

A

Zone that contains only source information about master servers for its zones only

DNS server hosting this zone obtains its information from a primary or secondary server

31
Q

Purpose of a Stub Zone

A

Used in parent domain to enable parent to keep up to date with name servers in sub domains and vice versa

Improved name resolution by enabling DNS server to rapidly locate stub zone’s list of name servers without need for querying other servers to locate appropriate DNS server

Simplify administration of DNS by enabling distribution of list of authoritative DNS servers throughout large enterprise network without need for hosting a large number of secondary zones

32
Q

Which zone is not possible with an Active Directory integrated zone

A

Secondary Zone

All DCs replicate information to each other and acts as master servers so no secondary zone needed

33
Q

Is zone transfer needed in an Active Directory integrated zone

A

No because DNS data is replicated with other AD DS directory partitions between DCs

34
Q

What happens if a DNS server hosted outside of AD DS fails

A

No possible to update its data

Unable to promote secondary DNS zone to primary

35
Q

What are some benefits of using an Active Directory integrated Zone? (3)

A

Fault tolerant.

Each writable domain controller acts as a master server and enables updates to all zones in which they are authoritative. No separate DNS zone transfer topology needed

Enhanced security, can configure dynamic updates to be secured

36
Q

What is a GlobalNames Zone

A

A primary zone used to enable single-lable name resolution

Used to provide backwards compatibility for WINS

37
Q

What is the minimum requirement for using GlobalNames Zone

A

DNS server must be 2008 or higher

38
Q

How do you limit the interfaces which DNS server listens for queries

A

Go the the Interfaces tab in DNS properties

Select or deselect specific IPs to be enabled on the server

39
Q

Why would a DNS server use an external forwarder

A

Reduce its processing load and network bandwidth

Protect internal DNS servers access from unauthorized Internet users

40
Q

What is a DNS forwarder

A

Relay DNS request from one server to another when the first server unable to process the request

41
Q

Steps on how does Forwarding protect internal DNS servers from unauthorized Internet users

A
  1. Client request for FQDN on zone where its preferred DNS server no authoritative on (ie. www.google.com)
  2. Local DNS server receives request but only has zone infor for the internal local domain. It forwards the request to external server (forwarder)
  3. DNS server finds IP of an external DNS server and forwards the request
  4. Forwarder attempts to resolve FQDN. If it can’t it forwards request to another forwarder to use iterative query
  5. When forwarder is able to resolve FQDN, it returns result to the internal DNS server by way of intermediate forwarders which then returns results to a client
42
Q

How to specify external forwarders

A

Properties of DNS Server>Forwarders tab
Click edit and then add IP of the forwader
Modify sequence in which forwarders are contacted with up and down command

43
Q

Powershell command for adding Forwarder

A

Add-DNSServerForwarder -IPAddress 205.59.247.45

44
Q

In what order will a DNS Server look to resolve a query

A
  1. Primary Zone
  2. Secondary Zone
  3. Cache
45
Q

Why would you want to disable recursion on a DNS server

A

Allow a DNS server provide resolution services only to other DNS servers because unauthorized users can use recursion to overload a DNS server’s resources to deny services

46
Q

How to disable Recursion on a DNS server

A

Go to properties of DNS server and go to advance tab

Make sure recursion tab is unchecked.

47
Q

Why would you enable to advanced feature ‘Enable BIND secondaries’

A

DNS servers normally use fast transfer that involves compression during zone transfers. UNIX servers running BIND version under 4.9.4 doesn support this compression

48
Q

What does the advance feature ‘Fail on load of bad zone data’ do

A

DNS server will not load zone data that contains certain types of errors. Checks name data using method selected in the Name Checking drop down in the advance tab of server properties

49
Q

What does enabling the advance DNS feature ‘Enable round robin’ do

A

Enable round robin for use with multiple records for the same host

50
Q

What does the DNS advance setting ‘Enable netmask ordering’ do

A

Prioritizes local subnets so when client queries for for host name mapped to multiple IP addresses, the DNs server preferentially returns IP address located on same subnet as requesting client

51
Q

What does advance DNS setting ‘Secure cache against pollution’ do

A

Prevent attackers from DNS spoofing by ignoring resource records for domain names outside the domain to which the query was originally directed

52
Q

What does the advance DNS setting ‘Enable DNSSEC validation for remote responses’ do

A

Reduce risk of DNS exploits by using digital signatures to validate DNS repsonses