Question about a question

Rearden · August 2007

I was doing the practice exams from the cisco press ICND book today and I got the following question:

The exhibit shows the output of a 'show ip protocols' command on a router. Which of the following statements can you prove based on the information in the command output?
A.) RIP routes are preferred over EIGRP.
B.) EIGRP on this router autosummarized network 192.168.22.0
C.) 100 or more sessions of EIGRP are present.
D.) The EIGRP timers have been changed.
E.) Any update that is received in the next 15 seconds indicates a topology change.

HICKORY#show ip protocols
Routing Protocol is "eigrp 100"
Outgoing update filter list for all interfaces is
Incoming update filter list for all interfaces is
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
EIGRP maximum hopcount 100
EIGRP maximum metric variance 1
Redistributing: eigrp 100
Automatic network summarization is in effect
Automatic address summarization:
192.168.22.0/24 for Serial1/0, Serial1/1
192.168.2.0/24 for FastEthernet0/0
Summarizing with metric 20512000
Routing for Networks:
192.168.2.0
192.168.22.0
Routing Information Sources:
Gateway Distance Last Update
(this router) 5 00:00:13
192.168.2.101 90 00:00:03
192.168.2.200 90 00:00:03
Distance: internal 90 external 170
HICKORY#

The answer that they were looking for was B, which makes sense. However, I think that E is also correct since with EIGRP, any update indicates a topology change. Am I mistaken?

Netstudent · August 2007

i rememeber that Q from ICND test engine. If they only give u one answer choice, go with D.

gabrielbtoledo · August 2007

D??? Are you sure, because I would go with B as well.

mikearama · August 2007

I think he meant B.

Netstudent · August 2007

actually I ment E sorry for the confusion...i had just gotten out of bed when I wrote that.

rjbarlow · August 2007

Routing Information Sources: 
Gateway Distance Last Update 
(this router) 5 00:00:13 
192.168.2.101 90 00:00:03 
192.168.2.200 90 00:00:03

Who is able to say if these updates are sent or received?

NeonNoodle · August 2007

rjbarlow wrote:
Routing Information Sources: 
Gateway Distance Last Update 
(this router) 5 00:00:13 
192.168.2.101 90 00:00:03 
192.168.2.200 90 00:00:03
Who is able to say if these updates are sent or received?

I'd say they were received because the title refers to sources.

NeonNoodle · August 2007

The answer that they were looking for was B, which makes sense. However, I think that E is also correct since with EIGRP, any update indicates a topology change. Am I mistaken?

E. is a true statement, but can it be proven from the output information given? It can, but only from the absence of information (there isn't any field indicating periodic updates because EIGRP does not send them) and not the presence of information. That's why B. is the correct answer while E. is not.

iDShaDoW · August 2007

Yeah, I chose B myself.

Although E may be true, that's not something you'd know by looking at the show ip protocol command.

That's more of something that's just a given if you know your protocols.

mikearama · August 2007

rjbarlow wrote:
Routing Information Sources: 
Gateway Distance Last Update 
(this router) 5 00:00:13 
192.168.2.101 90 00:00:03 
192.168.2.200 90 00:00:03
Who is able to say if these updates are sent or received?

On top of what Neon said, if these were being sent, then they're local routes. They would not then have a cost of 90... they'd be directly connected.

The fact that they have a cost of 90 indicates they are a result of eigrp, and therefore learned.

rjbarlow · August 2007

mikearama wrote:
rjbarlow wrote:
Routing Information Sources: 
Gateway Distance Last Update 
(this router) 5 00:00:13 
192.168.2.101 90 00:00:03 
192.168.2.200 90 00:00:03
Who is able to say if these updates are sent or received?
On top of what Neon said, if these were being sent, then they're local routes. They would not then have a cost of 90... they'd be directly connected.

The fact that they have a cost of 90 indicates they are a result of eigrp, and therefore learned.

Not so I think, this information is shifty.
5, 90, 90, doesn't represent the eigrp cost of the routing updates, but the administrative distance of the routing updates (is wrote on top, autosummarized eigrp routes are admin.distance of 5).
For me the first item means that the router has sent routing updates, while others two, stay for updates received from.

NeonNoodle · August 2007

rjbarlow wrote:
mikearama wrote:
rjbarlow wrote:
Routing Information Sources: 
Gateway Distance Last Update 
(this router) 5 00:00:13 
192.168.2.101 90 00:00:03 
192.168.2.200 90 00:00:03
Who is able to say if these updates are sent or received?
On top of what Neon said, if these were being sent, then they're local routes. They would not then have a cost of 90... they'd be directly connected.

The fact that they have a cost of 90 indicates they are a result of eigrp, and therefore learned.
Not so I think, this information is shifty.
5, 90, 90, doesn't represent the eigrp cost of the routing updates, but the administrative distance of the routing updates (is wrote on top, autosummarized eigrp routes are admin.distance of 5).
For me the first item means that the router has sent routing updates, while others two, stay for updates received from.

Well this is what the horse's mouth has to say about it:

cisco wrote:

Routing Information Sources

Lists all the routing sources the Cisco IOS software is using to build its routing table. For each source, you will see the following displayed:

•IP address

•Administrative distance

•Time the last update was received from this source

rjbarlow · August 2007

NeonNoodle wrote:
rjbarlow wrote:
mikearama wrote:
rjbarlow wrote:
Routing Information Sources: 
Gateway Distance Last Update 
(this router) 5 00:00:13 
192.168.2.101 90 00:00:03 
192.168.2.200 90 00:00:03
Who is able to say if these updates are sent or received?
On top of what Neon said, if these were being sent, then they're local routes. They would not then have a cost of 90... they'd be directly connected.

The fact that they have a cost of 90 indicates they are a result of eigrp, and therefore learned.
Not so I think, this information is shifty.
5, 90, 90, doesn't represent the eigrp cost of the routing updates, but the administrative distance of the routing updates (is wrote on top, autosummarized eigrp routes are admin.distance of 5).
For me the first item means that the router has sent routing updates, while others two, stay for updates received from.
Well this is what the horse's mouth has to say about it:

cisco wrote:

Routing Information Sources

Lists all the routing sources the Cisco IOS software is using to build its routing table. For each source, you will see the following displayed:

•IP address

•Administrative distance

•Time the last update was received from this source

Well, OK, but the router can't send routing updates to itself, agree?

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