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Kifle
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CCNA

Postby Kifle » Mon Oct 11, 2010 12:22 am

I'm completely sick of the business world. I have a great aptitude for it, but at this point, it is extremely undesirable, and the stress levels have gotten to the point of physical harm (high blood pressure, blurred vision, acid reflux... the whole nine). I can't do much without going back to school and finishing my education masters, and that is too much of a financial investment at this point (wife lost her job a week ago). So, I'm going back to the route I initially wanted to do after I graduated -- IT/network admin. I'm currently studying for my CCNA cert, and I expect to be done within a month or so. I was wondering if anyone here has gotten their CCNA or is currently in the process and wouldn't mind hooking up for some study time/note comparing.
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Re: CCNA

Postby teflor the ranger » Mon Oct 11, 2010 1:00 am

Sorry to hear about your troubles, but I should warn you that unless you want to stay in the middle career ranges in IT, it looks pretty much the same way from the top.

But at least you get to work in a certain field. Good luck.
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Re: CCNA

Postby kiryan » Mon Oct 11, 2010 2:55 pm

I have my CCNA and working on my CCNP. I should be able to answer any questions you have.

Best advice I can give you, is before you start your test, write down on your scratch paper / dry erase board the bits from 1-32 and the subnet masks associated with them and the network ranges / # of ips in each range. It is a lot easier to refer to a list than it is to think. I'm a double checker as well so it saves me double time.

There will be at least 2 scenario questions where they give you a picture of a network some information about it (x addresses, network addy = a) and about 5 questions usually whats the netmask here and how many ips are in this etc).

Also, know that ip subnet zero means you can use the .0 subnet (in the 90s you couldn't actually use 192.168.0.x, the "first" network was 192.168.1.x).

The sims were pretty easy questions in principle, I did have some trouble with the the second sim I did... not sure why, probably was just flustered since I didn't have much time left when I hit the first sim and even less for the second one. Because you can't go backwards after you pass a question, you need to be very conscious of how much time you have left and can use on the sims especially if the sims are at the end. I failed my first test (the combined test) 790 needed an 800 (out of 1000). I know several people who failed with the same score. There is a lot of speculation on the web that if you get either sim wrong, you fail the test. I think its possible that if you fail either sim but scored > 800 they just give you a 790. Pure speculation.

I don't know anyone who took the CCENT-1 and CCENT-2 tests to get their CCNA, they all took the combined which is supposedly harder. Cost wise the tests are ridiculous, I think the CCNA combiend is 225 and the 1&2 are $150 each. You used to be able to buy vouchers at a discount, I assume you still can. http://www.getcertify4less.com/cisco.asp They saved me at least a couple hundred dollars (I also have the CCSP) spammy, but legit as far as in my experience. They apparently buy "old" vouchers that were about to expire (or buy them in bulk and have to and blow out their expiring ones. They let them go for $80-100 but they're only good for 7-14 days. Basically, I got ready for a couple tests, waited for a voucher promo bought a voucher and immediately went up to take the test.

Getting certified was the best career move I ever made. Its sick how many more interviews you get and the difference in how they treat you at salary negotation.
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Re: CCNA

Postby Kifle » Mon Oct 11, 2010 5:41 pm

Thanks, Kiryan. I thought you had to have your CCNA Security before you could get a CCSP. That's actually the stopping point I'm anticipating. Maybe if I get bored in 10 years I'll move up, but I don't anticipate it. I was thinking of joining these with a CAPM from PMI. I would imagine with those three certs and maybe an MS cert, coupled with upkeep, I could make a decent career out of it and completely distance myself from the upper management I'm currently in. The only drawback I foresee to breaking into the IT field would be my undergraduate philosophy degree; however, it couldn't hurt either, I suppose.

Do you have facebook or any type of IM I could reach you at when I'm studying?
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Re: CCNA

Postby Kifle » Mon Oct 11, 2010 5:48 pm

Also, I'm not too far in my studies yet, but I move quickly. I'm pretty comfortable with IP ranges and different network classes. What's odd, is that the thing that is slightly hindering an even quicker pace is the theoretical backend -- the OSI layer model. I've never dealt much with the backend of software/hardware communication. I have a bit of undergrad software design under my belt, and years of hardware tech experience (not applicable on resumes), so... basically where I'm at in the coursebook (can't remember the name at the moment) are the first two chapters (roughly 100 pages) I ran through in a day. They covered the DoD/OSI model, data transfer (segments/packets/frames/etc), TCP/IP, some application layer protocols, ip ranges, network classes, common ports, binary/decimal/hex conversion... that type of shit. I think it starts the sims in one ore two chapters. I start subnets tonight. I'm able to ace all 5 study guides on it so far; however, again, there's a difference between memorizing an answer and fully comprehending the material, and, since this isn't a philosophy degree, I'm going to have to actually know the shit :)
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Re: CCNA

Postby kiryan » Mon Oct 11, 2010 6:23 pm

I don't social network at all. I don't really IM anymore. Durign the day I pretty much check the forums, in the evenings, I pretty much slave away while my wife studies for medical school.

At the time I took the tests, they didn't have a CCNA security so I don't know anything about that. CCNA was the starting point for all certs other than the CCDP which had a companinion to the CCNA called the CCDP.

Your philosophy degree might hurt you getting entry level interviews, but it'll help you get mid career level interviews where your lack of experience will hurt. They would prefer to see a IT degree if you're going into management, but low level management is going to depend on your ability to play politics. High level management will be looking for a masters in IT or business administration.

The study guides lay everything up there and you think you know it until you get a situational question.

For example heres one I should've known easily but didn't really know when I took the exam because no one had ever asked it before.

Computer a->switch->router1->internet->router2->computer b. they give you ips and mac addresses.

What is the IP address and mac address in the header of the packet at the lan side of router1 and at the internet side of router1 as a packet travels from A to B. Now I should've know and been able to infer it because macs control routing at layer 2 and IP is how layer 3, but i had to sit there and think about it for a few minutes and I'm not even sure I got it right. the correct answer I think is that the packet when it reaches the lan side of router 1 will have router1s internal mac and computer b's IP. on the internet side of router1, it will have router2's mac and computer b's ip. the routers aren't going to change the IP, the routers are going to read the packet to find the IP so it knows where to pass it next, but its not going to give the packet router2's IP. router 2 will pick up the packet because it has router 2's mac address not because it has router 2's IP. If there were several routers between router1 and router2, the packet exiting router1's internet interface would have the next router's mac address and the packet received on router2's internet interface will have router2's mac.

networking is easy, but its probably harder than you're thinking. I used to do Cisco installs and design networks and i failed the test. OSI model is important to understand like for the question above. especially the difference between layer 2 datalink (mac addresses), layer 3 (IP, routing), layer 4 (transport, aka protocol). a layer 4 function like error correction is not going to give a shit about the mac address and its not going to handled by the router or a switch. a layer 2 function is not going to care about the IP. Understanding this will help you clear the fog as you answer questions... or add fog if you're not really quite sure.

also, all my knowledge is from 2-3 years ago. the industry moves rapidly. In the late 90s, Cisco turned everything upside down with the advent of layer 2 routing (routing is a layer 3 function). By 3 or 4 years ago routers layer 3 devices were becoming aware of layer 4 stuff. Not sure if Cisco's forays into content are successful, but they were definitely trying to break into managing layer 4 stuff. OSI is critically important to understanding what is happening in networking.
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Re: CCNA

Postby Kifle » Mon Oct 11, 2010 8:17 pm

See, and this is kinda what is confusing to me: due to IP masquerading through NAT, wouldn't you be using the router 2 IP address in this scenario and then the router would then forward it along using its own table?
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Re: CCNA

Postby kiryan » Mon Oct 11, 2010 8:54 pm

I'm not talking about a nat situation... if you were nating then yes the router's IP would be the source IP and the router would maintain a map of local addresses/port to remote address/port and do translate the responses coming back in. The mac portion wouldn't change at all however. If it doesn't specifically mention nat, you should not assume nat. Its perfectly valid to have a computer with a public IP.

Another important thing to note is that the packet passing through the switch does not change the mac address... so if you were asked what mac is in the packet when it leaves the computer, the answer should be router1's local mac.

Nating is something you do need to know for the CCNA too. The sim I think I failed was natting, i couldn't remember syntax of one command that enabled the natting and I couldn't seem to come up with it using ?. I got a similar sim on the retest and it worked as I expected so I think I was just flustered because I was running out of time.
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Re: CCNA

Postby Kifle » Tue Oct 12, 2010 7:17 pm

Got it. Are there any other nuances about cisco testing that I should know? I saw you say to write your list down before taking the test. I just worked through the subnet chapter this morning before work (11 more to go!), and while I got it down very well, I could see how doing the mathematics and binary translation could be time consuming in a high stress testing situation; so, would I be allowed to bring in a written list of these things, or would this just be for study/memorization purposes. I couldn't see them actually allowing something like that.
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Re: CCNA

Postby Pril » Tue Oct 12, 2010 7:58 pm

Kifle wrote:Got it. Are there any other nuances about cisco testing that I should know? I saw you say to write your list down before taking the test. I just worked through the subnet chapter this morning before work (11 more to go!), and while I got it down very well, I could see how doing the mathematics and binary translation could be time consuming in a high stress testing situation; so, would I be allowed to bring in a written list of these things, or would this just be for study/memorization purposes. I couldn't see them actually allowing something like that.


When you sit down to do the test you have either paper or a whiteboard. Before you actually do the test write it down on one of them so that you can reference it during the test.
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Re: CCNA

Postby kiryan » Tue Oct 12, 2010 10:57 pm

right you basically have something like 5 minutes to "read the direction" before you start the test. During this time, scribble out a chart and the powers of 2 or whatever else might be useful.

This is what I did IIRC

power of 2, value, binary representation (in reverse), netmask.
2^0, 1, 00000000, 0
2^1, 2, 10000000, 128
2^2, 4, 11000000, 192
2^3, 8, 11100000, 224
2^4, 16, 11110000, 240
2^5, 32, 11111000, 248
2^6, 64, 11111100, 252
2^7, 128, 11111110, 254
2^8, 256, 11111111, 255
2^9, 512
2^10, 1024
2^11, 2048
2^12, 4096

Some people recommend writing the # of hosts and # of networks and netmasks and building a more complete chart. Whatever is easier for you. I'm pretty lazy and I always look at the 1s and 0s when I do subnet / # of hosts calculations.

Most people will make a chart that looks more like

vlsm, netmask, # hosts, block size (total # of addresses), # of networks
/30, 255.255.255.252, 2, 4, 64
/29, 255.255.255.248, 6, 8, 32
/28, 255.255.255.240, 14, 16, 16
/27, 255.255.255.224, 30, 32, 8
/26, 255.255.255.224, 62, 64, 4
/25, 255.255.255.224, 126, 128, 2
...

whatever works for you.

another thing that is tricky and you need to understand is "ip subnet zero" In the old days, you couldn't use the first or last network without doing "ip subnet-zero", now I believe it is enabled by default for the last 10 years. You'll have to read the questions / directions carefully to make sure you know whether you should be using/including the first and last subnets or not. For example, 192.168.x.x with a 255.255.255.0 subnet mask, you have 256 possible networks. However with "no ip subnet-zero" you can not use 192.168.0.0 or 192.168.255.0 so your total # of networks is 254. A question like this was on my CCNA, it may not be on the new stuff because its been default for so long now.

Some reading on it. http://www.cisco.com/en/US/tech/tk648/t ... 3f18.shtml
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Re: CCNA

Postby kiryan » Tue Oct 12, 2010 11:01 pm

The other section you really need to know is the routing protocols. I'd say 30% of the multiple choice is subnetting, 30% is routing and then miscellanous crap.

I don't remember questions on stupid crap like what address does RIP v1 broadcast updates on, but definitely needing to know when to use which protocols, what happens to the other routers when a router using that protocol fails etc...
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Re: CCNA

Postby Kifle » Wed Oct 13, 2010 2:01 pm

Thanks for the info, guys. I was actually pretty worried about having to do the spot calculations for all that subnetting. I have the powers memorized, and the ability to work out all the subnetting, but I imagine the time involved in doing a complete subnet for a class B would be a bastard -- unless you don't have to actually list the subnet/host range/broadcast.
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Re: CCNA

Postby Corth » Wed Oct 13, 2010 6:02 pm

Nobody is speaking English in this thread...
Having said all that, the situation has been handled, so this thread is pretty much at an end. -Kossuth

Goddamned slippery mage.
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Re: CCNA

Postby Kifle » Wed Oct 13, 2010 9:31 pm

How's this: The aforementioned poster (hereafter called "Kifle") laid claim that the object in question (hereafter referred to as "subnetting") may be difficult under the conditions laid out by the organization in questioned (hereafter referred to as "Cisco"); however, subnetting (hereafter referred to as "making the network smaller by incremental sectioning of the network") may, in fact, be simplified by using certain unnecessary, but, nevertheless, helpful tools (hereafter referred to as "crib sheets") in the expediency of making the network smaller by incremental sectioning of the network (hereafter referred to as "fucking with the network"). Kifle (hereafter referred to as "The Man") afterwords questioned the legality of such measures [cribbing]. In accordance to Kiryan's Act of 2010, stated as such in the heretofore mentioned messages (herein referred to as "posts"), with all liability of unintended or intended damages resulting in adhering to said Act laid solely on the deliverer (Herein referred to as "Neo"), one is given no greater (read: not necessarily equal to and possibly less than) than five minutes of preparation time before the CCNA exam (herein referred to as "fucking test"). The Man later acknowledged the utility of such an act, and gave explicit, but not contractually binding, receipt of Kiryan's Act with intent to adhere.

Does that work better, Corth?
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Re: CCNA

Postby kiryan » Wed Oct 13, 2010 11:43 pm

I nominate Kifle's post for "epic post of the year" in a non political thread.
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Re: CCNA

Postby kiryan » Wed Oct 13, 2010 11:56 pm

Having it written down is much more relaxing.

I don't know about you, but I've rarely had to do subnetting in the 16-128 range so netmasks of 224 and 192 were the hardest for me to remember. I don't recall any subnet questions > 4096 hosts. It was almost exclusively stuff in the 8 to 64 range.

You know stuff like you need 3 networks, one for 12 hosts, one for 16 and one for 63. Start with 192.168.0

192.168.0.0, 255.255.255.240 (14 hosts, hosts 0.1-0.14)
192.168.0.16, 255.255.255.224 (30 hosts, since next smaller is only good for 14, hosts 0.17-0.46)
192.168.0.48, 255.255.255.128 (126 hosts, since the next smaller is only good for 62, hosts 0.49-0.174 I believe)
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Re: CCNA

Postby Corth » Thu Oct 14, 2010 4:26 am

Kifle wrote:How's this: The aforementioned poster (hereafter called "Kifle") laid claim that the object in question (hereafter referred to as "subnetting") may be difficult under the conditions laid out by the organization in questioned (hereafter referred to as "Cisco"); however, subnetting (hereafter referred to as "making the network smaller by incremental sectioning of the network") may, in fact, be simplified by using certain unnecessary, but, nevertheless, helpful tools (hereafter referred to as "crib sheets") in the expediency of making the network smaller by incremental sectioning of the network (hereafter referred to as "fucking with the network"). Kifle (hereafter referred to as "The Man") afterwords questioned the legality of such measures [cribbing]. In accordance to Kiryan's Act of 2010, stated as such in the heretofore mentioned messages (herein referred to as "posts"), with all liability of unintended or intended damages resulting in adhering to said Act laid solely on the deliverer (Herein referred to as "Neo"), one is given no greater (read: not necessarily equal to and possibly less than) than five minutes of preparation time before the CCNA exam (herein referred to as "fucking test"). The Man later acknowledged the utility of such an act, and gave explicit, but not contractually binding, receipt of Kiryan's Act with intent to adhere.

Does that work better, Corth?


Makes perfect sense!
Having said all that, the situation has been handled, so this thread is pretty much at an end. -Kossuth



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Re: CCNA

Postby kiryan » Thu Oct 14, 2010 4:55 am

Now that I think about it I think you get 10-15 minutes to complete the reading the directions (also lets you get familar with some of the test mechanisms including the drag and drops and some basic simulations)
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Re: CCNA

Postby Kifle » Thu Oct 14, 2010 1:50 pm

kiryan wrote:Having it written down is much more relaxing.

I don't know about you, but I've rarely had to do subnetting in the 16-128 range so netmasks of 224 and 192 were the hardest for me to remember. I don't recall any subnet questions > 4096 hosts. It was almost exclusively stuff in the 8 to 64 range.

You know stuff like you need 3 networks, one for 12 hosts, one for 16 and one for 63. Start with 192.168.0

192.168.0.0, 255.255.255.240 (14 hosts, hosts 0.1-0.14)
192.168.0.16, 255.255.255.224 (30 hosts, since next smaller is only good for 14, hosts 0.17-0.46)
192.168.0.48, 255.255.255.128 (126 hosts, since the next smaller is only good for 62, hosts 0.49-0.174 I believe)


Ok, this is a bit bothersome. If we are talking about host space, why would you pick /28 class C when that leaves only 14 hosts per subnet? There would be no room for growth on any particular subnet. You would think you'd want to use the /27 for a currently 14 host/subnet internetwork. Also, wouldn't most questions concern themselves with class b or a networks due to growth problems in any business environment, or are you using class c in the example for simplicity reasons?
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Re: CCNA

Postby kiryan » Thu Oct 14, 2010 2:24 pm

The way I poised the question was you need 3 networks, one with 12 hosts, one for 16 and one for 63.

In practice depending on the situation yes you probably wouldn't want to use a /28 with 14 housts for a network you already know will have at least 12. On the other hand we use a /30 all the time when setting up connections between routers and because we only need 2 hosts (1 for each router). For example you have a direct fiber link between to buildings.

Also, if you are thinking that you can't mix and match subnets in the same class C you're not thinking correctly.

I'm using class C for simplicity, but most businesses don't need more than the class C space, you've got 256 networks of 256 hosts... how many businesses really need more than 65k addresses? The decision to deploy in class B is really more about the fact that consumer grade "routers" typically deploy in 192.168.0 or 192.168.1 not because you might need to grow into 1million addresses. I've walked into more than a few businesses who had a flat 10. because their former network admin wanted to leave room for growth. really you think you might someday need 16.7 million hosts? Even if you had 40 locations... with 200 employees each, you could easily handle that in the 192.168.0.0 space by supernetting class Cs and setting up 40 networks of 510 addresses each and still have 176 class Cs (192.168.80.0 192.168.255.255) for "growth".
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Re: CCNA

Postby Kifle » Thu Oct 14, 2010 2:37 pm

Lol, yeah, I suppose you're right. The book I have doesn't suggest to use class b or a explicitly, but the words generally used are "organizations generally go with at least a class b to ensure growth". But, I've questioned it for the exact reasons you're stating. Class C seems to have more than enough space for most small to medium companies. Also, I'm not at supernetting yet :)
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Re: CCNA

Postby kiryan » Thu Oct 14, 2010 2:45 pm

easy peasy

to subnet you go from /24 to /25 creating 2 networks of 128
to supernet you go from /24 to /23 which gives you an extra 256 hosts for a total of 512.

so if you were using 192.168.0.0 with a netmask of /23 you'd have 192.168.0.0-192.168.1.255 as your first network (net address 192.168.0.0, bcast 192.168.1.255), 2.0-3.255 for the second etc.
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Re: CCNA

Postby Kifle » Thu Oct 14, 2010 3:28 pm

Lol, the application is simple enough, and I may be able to answer my own question here, but here's a scenario:

The isp assigns me address 192.168.35.5. If I understand correctly, my router takes on that address, and then the router assigns my computer 192.168.0.2. So, while subnetting allows me to separate the node bits, supernetting somehow allows you to separate the network bits in the highest octet without confusing the system somehow?
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Re: CCNA

Postby kiryan » Thu Oct 14, 2010 6:14 pm

I always think about the bits when I sub/super net. There are faster more intuitive ways if you trust yourself to memorize forumlas.

Lets say you have an IP, 192.168.235.42 and a netmask and you want to calculate the network address and know how many hosts. Now normally, this would be a class C, 192.168.235.0, 255.255.255.0, 256 addresses. However we're going to use a netmask of 255.255.254.0 which is 23 bits instead of 24. Lets look at the bits

(Note that the bit order is most significant to least significant which is opposite of how we learn binary.)

192.168.235.42
11000000.10101000.11101011.00101010
subnet mask 255.255.254.0
11111111.11111111.11111110.00000000

subnet mask 255.255.255.0 (for reference)
11111111.11111111.11111111.00000000

The host bits on the 255.255.254.0 are the 0s starting on teh right to the first 1 on the left (total 9 vs total 8 for 255.255.255.0). Anything after that is a network bit. So its easy to see here that we have 2^9 addresses (512). Now since we were dealing with a class C and we're "combining" class C networks in a supernet, we just count up the borrowed bits, in this case 1. 2^1 is 2 so the supernet is 2 class Cs large (note you can't have a supernet that is 3 class Cs large, it would have to be 4 aka a power of 2). So now I know that starting at 192.168.0, a new network starts every 2. 192.168.2.0, 192.168.4.0, 192.168.6.0 etc... 235 our original ip belongs to 192.168.234.0 - 192.168.235.255.

The technical way to derive this is to take the 3rd octet from the ip and the mask
11101011 (235)
11111110 (252)

and it out
11101010 and convert to decimal = 234. The AND has the main effect of ensuring host bits come out 0. All you have to really do is take the IP and zero out the borrowed host bits.

IF we were doing the same thing with a 128 netmask
11111111.11111111.10000000.00000000 (128)

You can see you have 15 bits of host address. Really it does not matter what IP you are dealing with, the subnet masks controls with 100% certainity the # of addresses you have. 2^15 = 32768. Now if we have an IP of
x.x.253.212
x.x.11111101.11010100

and you and it with the 128 netmask

x.x.11111101.11010100 (x.x.253.212)
x.x.10000000.00000000 (x.x.128.0)
you get
x.x.10000000.00000000 or x.x.128.0 which is your network address.

If it was x.x.127.212
x.x.01111111.11010100
x.x.10000000.00000000 (x.x.128.0)
you get
x.x.00000000.00000000 (network address is x.x.0.0)

lastly, be sure you distinguish between host and address. I frequently use the terms incorrectly because there is no need to distinguish between the two for most people, but when you're answering questions if you say there are 2^15 hosts in a network isntead of 2^15 -2 (one for network address, one for broadcast) you'll get teh question wrong. There are 2^15 addresses, but only 2^15 -2 hosts.

also, I'd write out an octet in reverse binary too before the test!
_ _ _ _ _ _ _ _
128, 64, 32, 16, 8, 4, 2, 1
kiryan 2.0
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Re: CCNA

Postby kiryan 2.0 » Thu Oct 14, 2010 10:21 pm

Kifle,

This shit is totally useless. In 7 years of that post you will find that we will be conquered by aliens and use their networking technology, which has additional subnet fields and other fun stuff due to them having many many conquered worlds. You should defintely pursue the Mexico strip club due to the high demand in 2020 of half-alien/human breeds as slave labor (people don't like half-breeds in either culture) and strip clubs were the primary source of half-breeds.
Sarvis
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Re: CCNA

Postby Sarvis » Thu Oct 14, 2010 10:56 pm

kiryan 2.0 wrote:Kifle,

This shit is totally useless. In 7 years of that post you will find that we will be conquered by aliens and use their networking technology, which has additional subnet fields and other fun stuff due to them having many many conquered worlds. You should defintely pursue the Mexico strip club due to the high demand in 2020 of half-alien/human breeds as slave labor (people don't like half-breeds in either culture) and strip clubs were the primary source of half-breeds.



If you really wanted to help, you'd just give us some stock tips or superbowl scores so he could gamble...
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