VPC Flashcards
Whats the minimum CIDR block allowed and how many ips?
/28 (16 addresses)
Whats the maximum CIDR block allowed and how many ips?
/16 (65,536)
How can you get a single IPv6 assigned?
using a /56 CIDR block
Do IPv6 have a private type of ip address?
NO, no concept of public/private
what IP in a vpc is DNS available?
Base IP + 2 (10.0.0.1 is base, 10.0.0.3 will be dns)
How can you make ec2s in a VPC get a public dns host nam?
enableDnsHostnames option
How can you allow instances in the vpc to use the DNS ip address in the vpc?
enableDnsSupport option
How can you make a subnet in multiple AZ’s
you cant
⭐ can subnets’ ip CIDRs overlap with other subnets?
no, never
Can a subnet have a IPv6 CIDR
yes, but ONLY if the VPC it’s in has IP6 enabled
In subnet ip addressing, whats the network address?
The first IP (base ip) in the cidr
whats the “network +1 address” in vpc subnet cidr and what is it?
it’s the base ip +1 and it’s what aws uses as the vpc router
whats the “network +2 address” in the vpc subnet and whats is it?
ip address +2 above the base, and it’s used an the dns host
whats the network +3 address in the vpc subnet and what is it?
ip address +3 from the base, and it’s “reserved for future aws use” (but nothing is on it)
where is the broadcast ip in a vpc subnet and what is it for?
last ip address in the cidr range. It’s a network standard, but there’s no “broadcast” option in the vpc subnets.
what does the vpc router do by default?
routes trafic between subnets
what is the Main route table
it’s the default table associated with a subnet when no other route tables are associated
how many route tables can be associated with a vpc
1
when a destination matches mutiple destinations in a route table, which one is selected?
the more specific (i.e. higher /route in the cidr)
Whats the resilliancy of IGW?
Region resillient, i.e. you only need 1 for a region (and not per availablity zone)
when do NACLs intervieve?
whenever a request crosses the boundary of a subnet, but not
what NaCL rule number is used for a catch-all rule?
*
how many subnets can a NACL be associated with?
many (any!)
how many NACL’s can be associated to a subnet/
1 only
in vpc, what types of config(s) can you use to explicitly deny an ip address
NACL (but NOT security group)
can security groups reference aws logical resources?
yes
what are security groups attached to?
ENIs (network interfaces)
Do NAT gateways support security groups?
no
what kind of security can support NAT gateway?
NACLs
Do NAT gateways work with ipv4
yes
Do NAT gateways work with ipv6?
NO
