DNS & DHCP & NTP Flashcards

1
Q

DNS Record: A/AAAA

A

A: Address record maps hostname to IPv4
AAAA: Address record maps hostname to IPv6

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2
Q

DNS Record: CNAME

A

Canonical name is an alias for existing record
diontraining.com = www.diontraining.com

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3
Q

DNS Record: MX

A

Mail exchange record maps domain name to email server

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4
Q

DNS Record: NS

A

Denotes the authoritative name server for domain

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5
Q

DNS Record: PTR

A

Pointer record; used for reverse DNS lookups

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6
Q

DNS Record: SRV

A

Service Record
Used to specify a host & port for a specific service
Can specify a port along with our IP address

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7
Q

DNS Record: TXT

A

Designed initially to hold human readable code.
Now used to hold machine readable data

(DKIM: DomainKeys Indentified Email, SPF: Sender Policy Framework)

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8
Q

DNS Resolver (DNS Cache)

A

Temporary database that remembers the answers it received from the DNS server

Recursive Lookup: DNS Server will hunt it down & report back to your resolver

Iterative Lookup: DNS resolve will continually query DNS servers until it finds the one with the IP for the domain

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9
Q

DNS Zone Transfer

A

The process of sending DNS records data from the primary nameserver to a secondary name server.

Uses TCP to verify data is successfully sent by primary server & received by secondary server.

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10
Q

TTL (DNS)

A

Time to Live:
Tells the DNS resolver how long to cache a query before requesting a new one

In things like traceroute, it’s the number of hops until the packet is dropped.

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11
Q

Internal DNS

A

Allows cloud instances on the same network access each other using internal DNS names.

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12
Q

External DNS

A

Records created around the domain names we purchase from a central authority and use on the public internet.

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13
Q

DHCP

A

Provides an IP address to every machine on the network & eliminates configuration errors

IP, Subnet Mask, Default Gateway, DNS Server

UDP Port 67/68

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14
Q

DHCP: Scope

A

A list of valid IP addresses available for assignment/lease to a client computer or endpoint device on a given subnet

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15
Q

DHCP: Reservation

A

Excludes some IP addresses from being handed out to devices unless they meet a certain condition

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16
Q

DHCP: D-O-R-A Process

A

Discover, Offer, Request, Acknowledge

17
Q

DHCP Relay

A

Any host that forwards DHCP packets between clients & servers

Used when the client device & DHCP server are not located on the same subnet/network

18
Q

DHCP: Scope Options

A

Subnet mask
Default gateway
DNS server
Lease time

19
Q

DHCP: IP Helper

A

Forwards several different kinds of UDP broadcasts across the router & can be used in conjunction with DHCP relay

20
Q

NTP

A

Synchronizes clocks between systems communicating over a packet-switched, variable-latency data network.

UDP Port 123

NTPv4 (2010): Most current version

21
Q

DNS: Top Level Domains

A

Organizational Hierarchy:
.com
.net
.org

Geographic Hierarchy:
.uk
.fr
.it

22
Q

DNS: Second Level Domains

A

The site directly below the top level domain

Ex: diontraining.com

23
Q

DNS: Subdomains

A

Ex: chat.diontraining.com

24
Q

DNS: Host Level

A

The lowest & most detailed level in DNS hierarchy

Refers to a specific machine

25
Q

NTP

A

Synchronizes clocks between systems communicating over a packet-switched, variable-latency data network.

UDP Port 123

26
Q

NTP: Stratum

A

NTP Uses a hierarchal, semi-layered system of time sources.

Each layer of the hierarchy is a stratum. (Max: 15)
Stratum 0: Reference clocks
Stratum 1: First NTP servers (within usecs of Strat 0)
Stratum 2: Queries multiple Stratum 1 servers
Stratum 3: Pattern continues as you go up stratums

27
Q

DNS Record: SOA

A

Indicates which Domain Name Server (DNS) is the best source of information for the specified domain