CDN DNS & Domain Management 3

Question 1

What is the function of the DNS SOA (Start of Authority) record's 'Refresh' field?

Accepted Answer

How often secondary nameservers check for zone updates

Answer

The Refresh field tells secondary nameservers how frequently to poll the primary for zone changes.

Question 2

A CDN customer wants to use their own branded domain (white-label) for the CDN edge URL. Which DNS record type enables this without changing the apex domain?

Accepted Answer

CNAME

Answer

A CNAME aliases a subdomain (e.g., cdn.example.com) to the CDN's edge hostname, enabling white-label delivery.

Question 3

Why can't a CNAME record be placed at the zone apex (root domain) in standard DNS?

Accepted Answer

RFC 1034 prohibits CNAME coexistence with other record types such as SOA and NS at the same node

Answer

RFC 1034 states a CNAME cannot share a node with other records; since the apex needs SOA/NS, a CNAME there is invalid.

Question 4

What technology do many CDNs offer to work around the CNAME-at-apex limitation?

Accepted Answer

ANAME / ALIAS records (flattened CNAME)

Answer

ANAME/ALIAS records resolve the CNAME target server-side and return its IPs as an A record, bypassing the apex restriction.

Question 5

Which DNS query type asks the resolver to return all available record types for a given name?

Accepted Answer

ANY (QTYPE=255)

Answer

A DNS query with QTYPE=255 (ANY) requests all record types, though many resolvers now limit responses due to amplification abuse.

(CDN) Content Delivery Network Certification Practice Test

(CDN) Content Delivery Network Certification Practice Test

CDN DNS & Domain Management 3