Routing mode and point-of-presence selection service

A computer-implemented method comprising:

• under control of a hardware computing device configured with specific computer executable instructions:
• obtaining, at a first domain name system (DNS) server from a client computing device, a first DNS query, wherein a first point of presence (POP) of a content delivery network (CDN) service provider includes the first DNS server, wherein the first DNS query is associated with a requested resource;
• and
• responsive to obtaining the DNS query,
• determining a routing mode from a plurality of available routing modes for providing the requested resource based at least in part on a plurality of susceptibility factors;
• selecting (a) an alternative resource identifier associated with a second DNS server at a second POP of the CDN service provider or (b) an IP address of a cache component of the CDN service provider based at least in part on the determined routing mode;
• and
• transmitting, to the client computing device, the alternative resource identifier or the IP address.

A system comprising:

• a first point of presence (POP) associated with a content delivery network (CDN) service provider, wherein the first POP includes a first domain name system (DNS) server that receives a DNS query from a client computing device and a cache server in communication with the first DNS server, wherein the DNS query is associated with a requested resource, and wherein the first DNS server is operative to:
• dynamically determine, responsive to the DNS query, a suboptimal computing device for providing the requested resource;
• and
• transmit, to the client computing device, an identification of the suboptimal computing device in response to the DNS query.