| 1 | OSPF is not working between two routers. When debugging is turned on, the messages shown in Example 8-110 are received every 10 seconds. What is the problem? Example 8-110. The debug messages for Troubleshooting Exercise 1. RTR_EX1#debug ip ospf adj OSPF adjacency events debugging is on RTR_EX1# OSPF: Rcv pkt from 172.16.27.1, TokenRing0, area 0.0.0.25 : src not on the same network OSPF: Rcv pkt from 172.16.27.1, TokenRing0, area 0.0.0.25 : src not on the same network OSPF: Rcv pkt from 172.16.27.1, TokenRing0, area 0.0.0.25 : src not on the same network OSPF: Rcv pkt from 172.16.27.1, TokenRing0, area 0.0.0.25 : src not on the same network OSPF: Rcv pkt from 172.16.27.1, TokenRing0, area 0.0.0.25 : src not on the same network
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| 2 | Explain what problem is indicated by the debug messages in Example 8-111. Example 8-111. The debug messages for Troubleshooting Exercise 2. RTR_EX2#debug ip ospf adj OSPF adjacency events debugging is on RTR_EX2# OSPF: Hello from 172.16.27.195 with mismatched Stub/Transit area option bit OSPF: Hello from 172.20.1.1 with mismatched Stub/Transit area option bit OSPF: Hello from 172.16.27.195 with mismatched Stub/Transit area option bit OSPF: Hello from 172.20.1.1 with mismatched Stub/Transit area option bit OSPF: Hello from 172.16.27.195 with mismatched Stub/Transit area option bit OSPF: Hello from 172.20.1.1 with mismatched Stub/Transit area option bit OSPF: Hello from 172.16.27.195 with mismatched Stub/Transit area option bit OSPF: Hello from 172.20.1.1 with mismatched Stub/Transit area option bit
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| 3 | Explain what problem is indicated by the error messages in Example 8-112. Example 8-112. The error messages for Troubleshooting Exercise 3. RTR_EX3# OSPF: Send with youngest Key 10 OSPF: Rcv pkt from 10.8.1.1, Ethernet0 : Mismatch Authentication type. Input packet specified type 0, we use type 2 OSPF: Send with youngest Key 10 OSPF: Rcv pkt from 10.8.1.1, Ethernet0 : Mismatch Authentication type. Input packet specified type 0, we use type 2 RTR_EX3#
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| 4 | Explain what problem is indicated by the error messages in Example 8-113. Example 8-113. The error messages for Troubleshooting Exercise 4. RTR_EX4# OSPF: Send with youngest Key 10 OSPF: Rcv pkt from 10.8.1.1, Ethernet0 : Mismatch Authentication Key - Message D igest Key 10 OSPF: Send with youngest Key 10 OSPF: Rcv pkt from 10.8.1.1, Ethernet0 : Mismatch Authentication Key - Message D igest Key 10 RTR_EX4#
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| 5 | Explain what problem is indicated by the error messages in Example 8-114. Example 8-114. The error messages for Troubleshooting Exercise 5. RTR_EX5# %OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area must be virtual-link but not found from 10.8.1.1, Ethernet0 %OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area must be virtual-link but not found from 10.8.1.1, Ethernet0 RTR_EX5#
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| 6 | The configurations for the routers in Figure 8-58 follow. A: router ospf 15 network 192.168.50.224 0.0.0.31 area 192.168.50.0 network 192.168.50.240 0.0.0.15 area 0.0.0.0 area 192.168.50.0 authentication message-digest
B: router ospf 51 network 192.168.50.0 0.0.0.255 area 0
Routers A and B are not forming an adjacency. What is wrong? Figure 8-58. The network for Troubleshooting Exercise 6. 
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| 7 | Example 8-115 shows a link-state database from an area in which an unstable link exists. Based on the information shown, which link is the likely culprit? Example 8-115. The link-state database for Troubleshooting Exercise 7. RTR_EX7#show ip ospf database OSPF Router with ID (10.8.20.1) (Process ID 1) Router Link States (Area 0) Link ID ADV Router Age Seq# Checksum Link count 10.3.0.1 10.3.0.1 18 0x8000001B 0x6AF8 5 10.8.5.1 10.8.5.1 15 0x80000267 0xFDA0 6 10.8.20.1 10.8.20.1 478 0x8000001E 0xD451 4 Net Link States (Area 0) Link ID ADV Router Age Seq# Checksum 10.8.1.2 10.3.0.1 18 0x80000013 0xA747 RTR_EX2#
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