单项选择题 WhatisthepurposeofconfiguringrouterR1withthe"IPHelperaddress"command？（）

单项选择题 RIP and OSPF are configured on the routers as shown in the exhibit. R2 is configured with a two-way redistribution between RIP and OSPF domains. All routers can ping each other， but R1cannot see any of the OSPF routes in its routing table. What could the problem be？（）

单项选择题 Refer to the network shown below： R1 and R2 belong to the RIP routing domain that includes the networks 10.20.0.0/16 and 10.21.0.0/16. R3 and R4 are performing two-way route redistribution between OSPF and RIP. Anetwork administrator has discovered that R2 is receiving OSPF routes for the networks 10.20.0.0/16 and 10.21.0.0/16 and a routing loop has occurred. Which action will correct thisproblem？（）