A method comprising: receiving , at a first domain name system, DNS, server of a first data center, a first DNS query sent from a local DNS resolver , the first DNS query requesting a network address corresponding to a query domain name; responding to the first DNS query, from the first DNS server, by providing a first response to the local DNS resolver , the first response including both a network address of a reflector DNS server of a second data center , and the network address corresponding to the query domain name, both the first data center and the second data center corresponding to the query domain name; receiving , at the reflector DNS server, an additional DNS query , the additional DNS query being sent from the local DNS resolver and having embedded therein the network address corresponding to the query domain name; responding to the additional DNS query, from the reflector DNS server, by providing a second response to the local DNS resolver , the second response including a network address of a collector DNS server of the second data center , and having embedded therein the network address corresponding to the query domain name; receiving , at the collector DNS server, a final DNS query for the network address corresponding to the query domain name, the final DNS query being sent from the local DNS resolver and having embedded therein the network address corresponding to the query domain name; responding to the final DNS query, from the collector DNS server , with the network address corresponding to the query domain name; and determining , based on said communications between the local DNS resolver and the reflector DNS server and the collector DNS server of the second data center, one or more network performance measurements for communications between the local DNS resolver and the second data center. receiving , at a first domain name system, DNS, server of a first data center, a first DNS query sent from a local DNS resolver , the first DNS query requesting a network address corresponding to a query domain name; responding to the first DNS query, from the first DNS server, by providing a first response to the local DNS resolver , the first response including both a network address of a reflector DNS server of a second data center , and the network address corresponding to the query domain name, both the first data center and the second data center corresponding to the query domain name; receiving , at the reflector DNS server, an additional DNS query , the additional DNS query being sent from the local DNS resolver and having embedded therein the network address corresponding to the query domain name; responding to the additional DNS query, from the reflector DNS server, by providing a second response to the local DNS resolver , the second response including a network address of a collector DNS server of the second data center , and having embedded therein the network address corresponding to the query domain name; receiving , at the collector DNS server, a final DNS query for the network address corresponding to the query domain name, the final DNS query being sent from the local DNS resolver and having embedded therein the network address corresponding to the query domain name; responding to the final DNS query, from the collector DNS server , with the network address corresponding to the query domain name; and determining , based on said communications between the local DNS resolver and the reflector DNS server and the collector DNS server of the second data center, one or more network performance measurements for communications between the local DNS resolver and the second data center. <EOS>