Domain name resolution resource allocation

A method for delivering content over the Internet using a plurality of points of presence (PoPs) that are geographically distributed, wherein the method comprises:

• utilizing a DNS server of one of the PoPs to maintain a list of content servers that are considered available for domain resolution service (DNS) resolution requests for the one of the PoPs based on at least one utilization measurement of at least one of the content servers,
• wherein if the utilization measurement exceeds a first threshold, the at least one of the content servers is removed from the list of content servers that are considered available, and
• if the utilization measurement falls below a second threshold, the at least one of the content servers is added to the list of content servers that are considered available,
• the second threshold being lower than the first threshold;
• receiving a first domain resolution request at a first point in time, at the DNS server;
• producing a first DNS solution utilizing the DNS server, the first DNS solution corresponding to the first domain resolution request, and including a first plurality of IP addresses of content servers taken from the list of content servers that are considered available at the first point in time;
• returning the first DNS solution from the PoP;
• receiving a second domain resolution request at a second point in time, at the DNS server;
• producing a second DNS solution utilizing the DNS server, the second DNS solution corresponding to the second domain resolution request, and including a first plurality of IP addresses of content servers taken from the list of content servers that are considered available at the second point in time;
• and
• returning the second DNS solution from the PoP, the second DNS solution differing from the first DNS solution based on a difference in the list of content servers between the first and second points in time.

A point of presence (PoP) of a content delivery network (CDN) for delivering content over the Internet, the PoP comprising:

• a plurality of content servers;
• and
• a domain resolution service (DNS) server that is configured to:
• determine that a given one of the content servers should be removed from a list of content servers in the PoP that are considered available, when a utilization measurement of the given one of the content servers exceeds a first threshold;
• determine that the given one of the content servers should be restored to the list of servers considered available, when the utilization measurement of the given content server is lower than a second threshold, wherein the second threshold is lower than the first threshold;
• and
• produce a DNS solution, including a plurality of IP addresses of content servers, in response to a domain resolution request, each of the IP addresses corresponding to a content server included in the list of content servers that are considered available when the DNS solution is produced.