Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

CCNA Exam: Router's configuration

Posted on 2009-05-14
2
Medium Priority
?
1,853 Views
Last Modified: 2012-08-14
Hi,

1) This is related to the CCNA Exam.
2) This is related to the discussion at one of the prep test
3) There is an error of this router's configuration:
R1#config t
R1(config)#int fa0/0
R1(configi-if)#ip address 192.168.1.17 255.255.255.0
R1(config-if)#no shutdown
R1(config-if)#exit
R1(config)#int s0/0
R1(config-if)#ip address 192.168.1.65 255.255.255.240
R1(config-if)#no shutdown
  / 192.168.1.0  overlaps with FastEthernet0/0
4)The given answer: The subnet mask of the FastEthernet interface should be changed to 255.255.255.240
5)My question: Please say it with your own wordings, but you can give any "links" if necessary: i) Could you show me why we have to change the subnet mask of the FastEthernet interface to 255.255.255.240
6) Thank you

tjie
0
Comment
Question by:tjie
2 Comments
 
LVL 8

Accepted Solution

by:
ludo_friend earned 1040 total points
ID: 24391043
ip address 192.168.1.17 255.255.255.0 specifies that the address is part of the 192.168.1.0/24 subnet
(fyi)
24 mask bits = 255.255.255.0
28 mask bits = 255.255.255.240
192.168.1.0/24 subnet has a host range of 192.168.1.1 to 192.168.1.254 (0 being network and 255 being broadcoast)
192.168.1.17/28 subnet has a host range of 192.168.1.17 to 192.168.1.30 (16 being network and 31 being broadcast)
192.168.1.65/28 subnet has a host range of 192.168.1.65 - 192.168.1.78 (64 being network and 79 being broadcast)

if fa0/0 was left as /24, you can see that the host range includes the host range of 192.168.1.64/28 which conflicts. simply speaking, you can't overlap the subnets.  

have a play with the subnet calculator to get an idea of how subnetting affects your ranges.
http://www.subnet-calculator.com/




0
 
LVL 23

Assisted Solution

by:that1guy15
that1guy15 earned 960 total points
ID: 24391064
The two subnets overlap.

Int f0/0's ip subnet range is from 192.168.1.0 - 192.168.1.255 (.1 is the subnet # and .255 is the broadcast).

Int s0/0's ip subnet range is from 192.168.1.64 - 192.168.1.79 (64 is the subnet # and 79 is the broadcast).

A router can not have two interfaces in the same subnet range.

Here is a link to a subnet calculator to help you determine ranges and subnetting.
http://www.subnet-calculator.com/

My recommendation though is you will need to be able to subnet quickly in your head for the CCNA.
0

Featured Post

Important Lessons on Recovering from Petya

In their most recent webinar, Skyport Systems explores ways to isolate and protect critical databases to keep the core of your company safe from harm.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

How to set-up an On Demand, IPSec, Site to SIte, VPN from a Draytek Vigor Router to a Cyberoam UTM Appliance. A concise guide to the settings required on both devices
Sometimes clients can lose connectivity with the Lotus Notes Domino Server, but there's not always an obvious answer as to why it happens.   Read this article to follow one of the first experiences I had with Lotus Notes on a client's machine, my…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

972 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question