Proxy Arp – who needs a gateway!!!!!!?

 

Ever wondered why when you don’t have a gateway or you use the wrong one, you still get routing?  Well this maybe why! Proxy Arp is enabled on the gateway or routers.

Click on link to read PDF all about Proxy ARP command:

https://itdaddy.files.wordpress.com/2008/05/proxyarp.pdf

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Real life test using arp table

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To prove your gateway has Proxy Arp enabled, do this:

1. If your current subnet is /24 change your PC TCP/IP settings to /16

2. then ping a ip you know is on a different subnet. say 192.168.2.1

3. once you ping fire up command prmpt and type in “arp -a” should

see the same mac address ast your gateway as the mac for the 192.168.2.1

if so you are using Proxy ARP! yeah baby yeah!

—————————————–

Here is my test with say a /16 vs /24 bit subnet using the pdf eample from cisco you gave me…

arp table on my pc is this(mock ip addresses not reall ones) but the same concept:

say i pinged server2 192.168.2.1
and i changed my subnet mask from 24 to 16
ping srv2 with using DNS server but arp shows this:

 
 Internet Address      Physical Address      Type
192.168.1.1           00-e0-18-04-96-af     dynamic
192.168.1.2           00-15-2b-e6-fe-41     dynamic  – gateway
192.168.1.10          00-30-48-60-37-2c     dynamic
192.168.1.13          00-00-74-d4-8a-95     dynamic
192.168.1.18          00-1b-fc-35-c0-73     dynamic
192.168.1.93          00-e0-81-2a-fa-d3     dynamic
192.168.2.1           00-15-2b-e6-fe-41     dynamic  – server 2 ip

 

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4 Responses to “Proxy Arp – who needs a gateway!!!!!!?”

  1. Aragoen Celtdra Says:

    Yo, what’s up brotha! Looks like you have been very busy with all these write-ups. Very impressive.

    I myself have been very lazy about updating my blog. But nothing to be concerned about, I’m still keeping my studies current. I suppose I need to ramp up my blogging to keep up with you ;).

    Talk to you later…

  2. Hey, I am only using this blog to work on harder stuff. I plan on bringing to the blog NAT, ACL, EIGRP, OSPF and keep the easy stuff like PAP, CHAP and PPP and HDLC type combined in one lab if I decide to put on this blog. I only blog stuff that is much more detailed. Check out the ccna academy link on my links above. They have tons of exam questions I plan on studying myself…I have 70 days till my ccna 802 exam. It is for 7 Aug 2008. I am kicking it down…….it is hammer time…
    Later man! Blog only if it helps you and if it helps you it might help others that is what I do. I only blog stuff that I have done and helps me focus better, and I hope it helps others as well….get herrrrr done!

  3. Aragoen

    dude use that notepad program that is free then I do screen shots
    paste into PAINT.net and crop and save as PNG and upload to blog
    bam! done!

  4. oops.. don’t know what happened there. please delete the blank post =)

    i myself have been taking a lot of notes and considered putting it up on my blog to maybe help others – if anything to share about my study methods. That’s what I do when i read other people’s blogs. I sorta use it as a gauge to see where I am compared to where others are. unfortunately there’s not a lot of CCNA bloggers out there. I see a lot of CCIE blogs though so those can help if/when I’m studying for CCIE. but that’s a long ways from now.

    Anyway, good luck on the test.

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