Routing Flashcards

1
Q

DNS

A

used to convert human-friendly domain names into an IP address

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2
Q

IPv4

A
  • older
  • are running out
  • 32-bit friendly
  • only has 4 billion addresses
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3
Q

IPv6

A
  • created to solve the depletion issue with IPv4
  • 128 bits
  • 340 undecillion addresses
  • eventually we’ll all need to migrate to IPv6
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4
Q

Top-Level Domain

A

last word of a domain name

- controlled by IANA

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5
Q

Second Level Domain

A

the second-to-last word in a domain name

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6
Q

Domain Registrar

A

an authority that can assign domains under top-level domain names and register them with InterNIC

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7
Q

Examples of Top-Level Domains

A

.com .gov .edu .org, etc.

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8
Q

InterNIC

A

a service of ICANN which enforces uniqueness of domain names

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9
Q

DNS Record Type: SOA Record

A

supplies:

  • name of server that supplied data for that zone
  • administrator of the zone
  • current version of the data file
  • default # of seconds for the Time-To-Live on resource records
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10
Q

DNS Record Type: NS Record

A

used by top-level domain servers to direct traffic to the content DNS server that contains the authoritative DNS records

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11
Q

DNS Record Type: A Record

A

Address Record

  • fundamental type of DNS record
  • used by a computer to translate the name of a domain to an IP address
  • most common kind of DNS record
    ex: translates http://www.acloud.guru to http://123.10.10.80
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12
Q

Time to Live (TTL)

A
  • how long the DNS record gets caches
  • the lower the TTL the faster the changes propagate across the internet
  • important to reduce TTLs before making a big change or migration
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13
Q

DNS Record Type: CNAME

A
  • canonical name
  • used to resolve one domain name to another
    ex: www.example.com points to example.com
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14
Q

AWS Alias Records

A
    • used to map resources record sets in your hosted zone to load balancers, CloudFront distributions or S3 buckets
      ex: map www.example.com to elb124.elb.amazonaws.com
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15
Q

Naked Domain Names

A

a. k.a. Zone Apex Records
- just the domain name without a subdomain
ex: http://acloudguru.com
- CNAMES cannot be used on Naked domain names, but an A Record/Alias can

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16
Q

7 routing policies available on Route 53

A

1) simple routing
2) weighted routing
3) latency-based routing
4) failover routing
5) geolocation routing
6) geoproximity routing (traffic flow only)
7) multi-value answer routing

17
Q

Where do you create routing policies?

A

Route 53 -> Hosted Zones -> Create new record

18
Q

Route 53 Exam tips

A
  • understand difference between a CNAME and an Alias record
  • given the choice for CNAME or Alias record, always choose the Alias record
  • understand DNS record types: SOA, CNAME, NS, A
19
Q

Route 53 Simple Routing Policy*

A

one record goes to multiple IP addresses

when user request the site, they are given an IP at random

20
Q

Route 53 Failover Routing Policy

A

used when you want an active/passive setup*

eg. you have a primary site in one AZ and a secondary DR site in another AZ
- route 53 monitors the health of your endpoints with a health check*
- route 53 will failover to the secondary when necessary

21
Q

Route 53 Geolocation Routing Policy

A

lets you choose where your traffic will be sent based on the geographic location of your end users *

  • can be country or continent
  • use cases:
  • – localization for different countries
  • country-based regulations
22
Q

Route 53 Traffic Flow

A

uses a combination of geographic location, latency, availability to route traffic

23
Q

Route 53 Geoproximity Routing

A
  • requires Traffic Flow*
  • lets Route 53 route traffic to resources based on the geographic location of your users and your resources
  • optionally can choose to route more or less traffic to a given resource using a bias
  • very complex, probably not on exam
24
Q

bias

A

expands or shrink the size of a geographic region

25
Q

Route 53 Latency Routing Policy

A

allows you to route traffic based on the lowest network latency for your end user (i.e. which region will give them the fastest response times)

26
Q

Route 53 Multivalue Answer Routing

A
  • lets you configure Route 53 to return multiple values (such as IP addresses) in response to DNS queries (like simple routing does)
    AND
  • lets you do health checks
27
Q

Route 53 Weighted Routing Policy

A

allows you to split traffic based on weights assigned. You can send a percentage of traffic to each site.

28
Q

Route 53 Health Checks

A
  • can be set on individual EC2 or ELB resources
  • can send alerts via SNS
  • if a record fails a health check, it is removed from Route 53 until it passes again