Correct Answer : Option (D) : by contacting remote DNS server
Explanation : Whenever a request is received at server from other domains, it handles this situation by contacting remote DNS server.
Correct Answer : Option (A) : DUAL
Explanation : EIGRP uses the DUAL algorithm for finding shortest path. DUAL stands for diffusing update algorithm and it is used to prevent routing loops by recalculating routes globally.
Correct Answer : Option (B) : 170
Explanation : Routers use the metric of administrative distance to select the best path when there are different routes to the same destination from two different routing protocols as it is a measure of reliability of routing protocols. Administrative distance for external EIGRP is 170.