1. A computer-implemented method, in a content delivery (CD) network (CDN) comprising multiple delivery service endpoints running on a plurality of devices, each of said delivery service endpoints constructed and adapted to deliver resources on behalf of one or more content providers, a plurality of said multiple delivery service endpoints comprising a group, wherein each node in said group has at least one kind of responsibility relating to delivery of resources, the method comprising: (A) receiving, at said node, a request relating to a particular resource; (B) determining what kind of responsibility said node has for said request, said determining being based on at least one kind of responsibility assigned to said node for requests relating to said particular resource, wherein the kind of responsibility the node has for the particular resource is defined in a policy associated with the particular resource, wherein the policy is defined for a group of resources, wherein the group of resources comprises a property, wherein a property comprises one or more resources associated with a particular content provider of said one or more content providers and delivered by the CDN on behalf of the particular content provider; and (C) based on said determining in (B), attempting to process said request in accordance with kind responsibility assigned to said node for requests relating to said particular resource, wherein the policy is based on one or more of: cacheability, and size of the resource; and wherein the kind of responsibility that can be assigned to a node is taken from a discrete set of responsibilities comprising of: non responsible, cache responsible, and fill responsible; and wherein there is a responsibility set corresponding to each kind of responsibility in said discrete set of responsibilities, and wherein each node in the group is assigned to at least one responsibility set.