200-301 · Question #755
Refer to the exhibit. If the router Cisco returns the given output and has not had its router ID set manually, what value will OSPF use as its router ID?
The correct answer is D. 2.2.2.2. In the absence of a manually configured OSPF Router ID, the router will select the highest IP address of an active loopback interface; if no loopbacks exist, it chooses the highest IP address of an active physical interface.
Question
Refer to the exhibit. If the router Cisco returns the given output and has not had its router ID set manually, what value will OSPF use as its router ID?
Exhibits
Options
- A192.168.1.1
- B172.16.1.1
- C1.1.1.1
- D2.2.2.2
How the community answered
(37 responses)- A8% (3)
- B5% (2)
- C3% (1)
- D84% (31)
Why each option
In the absence of a manually configured OSPF Router ID, the router will select the highest IP address of an active loopback interface; if no loopbacks exist, it chooses the highest IP address of an active physical interface.
192.168.1.1 would only be selected if it were the highest active IP and no higher IP existed on any loopback or other active physical interface.
172.16.1.1 would only be selected if it were the highest active IP and no higher IP existed on any loopback or other active physical interface.
1.1.1.1 would only be selected if it were the highest active IP and no higher IP existed on any loopback or other active physical interface.
OSPF Router ID selection prioritizes a manually configured ID. If not configured, it selects the highest IP address among all active loopback interfaces. If no loopbacks are present, it chooses the highest IP address among all active physical interfaces. Thus, 2.2.2.2 must be the highest among these.
Concept tested: OSPF Router ID selection process
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_ospf/configuration/15-mt/iro-15-mt-book/iro-ospf-basic.html
Topics
Community Discussion
No community discussion yet for this question.