DNS Cache

Question 1

What are the three types of DNS Cache?

Answer 1

1) Transparent
2) Resolver
3) Validating Resolver

Question 2

What is caching?

Answer 2

DNS responds and subsequent queries allows the BigIP DNS to respond to clients quickly.

Question 3

What are the two reasons for DNS caching?

Answer 3

1) Allows fast responses to clients.
2) Reduces the number of queries to be resolved, and can handle multiple queries from clients.

Question 4

What is a transparent cache?

Answer 4

Queries public DNS servers and consolidates content that would otherwise be cached across multiple external resolvers.
F5 recommends forwarding queries to a pool of local DNS servers if it cannot be answered by the cache.

Question 5

What is a resolver cache?

Answer 5

It creates a resolver DNS to resolve DNS queries and cache the responses. It contains messages, resource records, and the nameservers the system queries to resolve DNS queries.

Question 6

What is a validating resolver cache?

Answer 6

Using DNSSEC, it recursively query public DNS servers, validate the identity of the DNS server sending the responses, and then cache the responses.
It contains messages, resource records, and the nameservers the system queries to resolve DNS queries.

Question 7

True or false: F5 recommands using local BIND instance on the BIG-IP system to act as an external DNS resolver.

Answer 7

False

Question 8

True or fase: The resolver and validating resolver DNS caches also contain a nameserver cache.

Answer 8

True

Question 9

True or false: the validating resolver also has a key cache.

Answer 9

True

Question 10

Where do you create the BigIP DNS cache?

Answer 10

DNS > Settings > Caches

Question 11

What are the three steps in configuring a DNS cache?

Answer 11

1) Create the cache - either transparent, resolver, or validating resolver.
2) Apply it to a DNS profile.
3) Assign the DNS profile to a listener.

Question 12

If using a DNS pool for queries, what would need to be configured?

Answer 12

1) DNS monitors
Add site to be queried/monitored.
2) DNS pool
Apply the monitors to the pool

Question 13

True or false: With DNS resolver cache, you would enable the local BIND server in the configuration.

Answer 13

False

Question 14

True or false: The BigIP DNS can be authoritative for local zones.

Answer 14

True

Question 15

True or false: you can configure resolver or validating resolver to forward specific nameservers for a specific zone.

Answer 15

True