In order to obtain close-to-reality Internet maps, IP aliases resolution allows identifying IP addresses belonging to the same router. Mainly, active probing is used for IP aliases resolution following direct and indirect schemes. Also, different types of probe packets are used (ICMP, UDP, etc.) focusing on different header fields and characteristics of IP and higher layers. Responsiveness of routers is different not only in the number of response packets received, but also in the validity of those packets to be used in IP aliases identification. Therefore, specific behavior of routers generating those response packets can decide the success or failure of specific IP aliases resolution methods. In this paper, an in-depth analysis of router behaviors is provided considering not only router responsiveness, but also the validity of those responses to be used in IP aliases resolution. Our results show that although responsiveness is better for indirect probing, direct probing with ICMP Echo probe packets and IPID-based behavior provide the best identification ratio for IP aliases resolution.