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RID Question

triplebenctriplebenc Member Posts: 28 ■□□□□□□□□□
Hey, I came along this question and I was curious to why they say physical address is the right answer rather than logical. For some reason I thought that physical would be the right answer, but he also configured logical which which then lead me to believe that would be the right answer. I guess I thought that phyical is the highest RID until you configure logical interfaces, then logical would be the RID.

You work as network administrator at ****.
Your trainee is configuring a router with both physical and logical interfaces.
He asks you what factor determines the OSPF router ID.
What should you tell him?
A. The lowest network number of any interface.
B. The lowest IP address of any logical interface.
C. The lowest IP address of any physical interface.
D. The highest network number of any interface.
E. The highest IP address of any logical interface.
F. The highest IP address of any physical interface.

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    2lazybutsmart2lazybutsmart Member Posts: 1,119
    Logical interfaces preceed any physical ones when it comes to choosing the RID.
    Exquisite as a lily, illustrious as a full moon,
    Magnanimous as the ocean, persistent as time.
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    triplebenctriplebenc Member Posts: 28 ■□□□□□□□□□
    So why then, is F the correct answer? when i thought it should be E
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    2lazybutsmart2lazybutsmart Member Posts: 1,119
    F cannot be the correct answer.

    Loopback interfaces take precedence over physical interfaces. That's a rule. The reason Cisco did it that way is so that you have permanent stable RIDs for easier administration. Otherwise, when links go down, a new RID must be generated. And of course you know that a loopback interface never goes down.
    Exquisite as a lily, illustrious as a full moon,
    Magnanimous as the ocean, persistent as time.
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    triplebenctriplebenc Member Posts: 28 ■□□□□□□□□□
    Alright thanks, so it looks like the practice test was incorrect then. I sat and thought about that question for like 10 min. on how the heck they got F. Glad to know they were wrong.
    Thanks
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    GogousaGogousa Member Posts: 68 ■■□□□□□□□□
    Be careful with the practice tests. Get them from a reliable source.
    I don’t know which one are you using but there are a lot of practice tests out there that have the wrong answers at purpose.
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    YankeeYankee Member Posts: 157
    Loopbacks take precedence but not ANY virtual interface. A frame relay subinterface is virtual. A multilink bundle is virtual. There are many types of virtual interfaces.

    Yankee
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    cisco_troublecisco_trouble Inactive Imported Users Posts: 78 ■■□□□□□□□□
    What you are saying is that if there is a loopback and serial int, if the serial int has a higher ip it still takes the loopback ip? So its the loopback int highest ip under any circumstances? or is it the highest ip under all configured interfaces? hmm...
    "To strive, to seek, to find, and not to yield."
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