RE: Class C summarization question [7:48367]
I don't think its unreachable. Cisco tests OTOH Most people use the 2^n-2 rule for determining the number of available/usable networks. The -2 is there because of the need to remove the network and broadcast subnet. I don't write the rules, I just question them :) I agree with you 100% that there are 16 subnets. I was trying to point out that those that we bringing up the fact that in the old world only 14 were available were not reading the question correctly. It didn't ask for usability, it asked for quantity. As I am sure you are aware, as you take more and more Cisco tests, it becomes important to clarify what they are actually asking for, not what would make sense for them to ask for... Its also important to note that IP subnet zero is still needed on Cisco eq for it to route/subnet properly, they just enabled it by default now... Thanks Larry -Original Message- From: Chuck [mailto:[EMAIL PROTECTED]] Sent: Friday, July 12, 2002 3:13 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] ah, but that is old world classful thinking. as per RFC 1812, effectively there is no such thing as subnet zero any longer. per that RFC, all routers SHOULD route to any address in the form of network:host, or network:subnet:host. subnet zero is a holdover from the old world. it is there because of the concern that there is still so much old world equipment out there. RFC 1812 is dated June 1995, and one wonders how long it takes in practical terms for all manufacturers and all software stack writers to get all their stuff up to standard.. not to mention how long it takes for the old stuff to be removed from production. hhhm. a brief look through ARIN seems to indicate that assignments are not made out of subnet zero space but that is still a different question. a summarization produces a single route where several existed before. if you see a summary 192.1.0.0/16, why would you think that 192.1.0.0/24 is unreachable? Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Just to jump in late on this, but... The question doesn't ask how many of those class C are usable, which would be dependant on subnet O, but instead the question was how many you would be able to summarize. A /20 would in fact summarize 16, 14 of which are useable without subnet zero... Thanks Larry -Original Message- From: Dain Deutschman [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 10, 2002 4:05 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Hey everyone, Thanks for all of your help. I have decided that 16 must be correct since it makes perfect sense and most of you back that up as well. I think the test question was just plain wrong. Anyway...I passed the CCNP Routing exam today so I'm pretty happy. : ) Groupstudy is a great learning resource. Thanks everyone. Dain. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48734t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Larry, I'm only beating this dead horse for the CCNA/ beginner types on the list, who really do need to learn to distinguish between the function of a route summary versus the practicality of subnetting classful networks such that subnet zero becomes an issue. while I wouldn't bet the house on it, I suspect that even on Cisco tests, there would not be question about summarization where the subnet zero, all ones subnet count ( 2^n-2) would be the right answer. ( although I would not be surprised to see this in some of the study materials, given what I know about how quality control is valued with certain publishers. ) I was more concerned that it became a point of disagreement during the course of this thread, indicating that there were some who did not understand the why of things. Is ip subnet-zero enabled by default now? Which IOS release? Last I checked ( command reference for 12.2 ) the default was still disabled IP classless is now enabled by default, but not subnet-zero. this could have changed. the docs on CCO tend to be a bit behind reality. Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I don't think its unreachable. Cisco tests OTOH Most people use the 2^n-2 rule for determining the number of available/usable networks. The -2 is there because of the need to remove the network and broadcast subnet. I don't write the rules, I just question them :) I agree with you 100% that there are 16 subnets. I was trying to point out that those that we bringing up the fact that in the old world only 14 were available were not reading the question correctly. It didn't ask for usability, it asked for quantity. As I am sure you are aware, as you take more and more Cisco tests, it becomes important to clarify what they are actually asking for, not what would make sense for them to ask for... Its also important to note that IP subnet zero is still needed on Cisco eq for it to route/subnet properly, they just enabled it by default now... Thanks Larry -Original Message- From: Chuck [mailto:[EMAIL PROTECTED]] Sent: Friday, July 12, 2002 3:13 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] ah, but that is old world classful thinking. as per RFC 1812, effectively there is no such thing as subnet zero any longer. per that RFC, all routers SHOULD route to any address in the form of network:host, or network:subnet:host. subnet zero is a holdover from the old world. it is there because of the concern that there is still so much old world equipment out there. RFC 1812 is dated June 1995, and one wonders how long it takes in practical terms for all manufacturers and all software stack writers to get all their stuff up to standard.. not to mention how long it takes for the old stuff to be removed from production. hhhm. a brief look through ARIN seems to indicate that assignments are not made out of subnet zero space but that is still a different question. a summarization produces a single route where several existed before. if you see a summary 192.1.0.0/16, why would you think that 192.1.0.0/24 is unreachable? Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Just to jump in late on this, but... The question doesn't ask how many of those class C are usable, which would be dependant on subnet O, but instead the question was how many you would be able to summarize. A /20 would in fact summarize 16, 14 of which are useable without subnet zero... Thanks Larry -Original Message- From: Dain Deutschman [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 10, 2002 4:05 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Hey everyone, Thanks for all of your help. I have decided that 16 must be correct since it makes perfect sense and most of you back that up as well. I think the test question was just plain wrong. Anyway...I passed the CCNP Routing exam today so I'm pretty happy. : ) Groupstudy is a great learning resource. Thanks everyone. Dain. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48737t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
By all means beat the dead horse. I would rather people learn the how's and why's , instead of just a memorization of what to answer. I looked up the 12.1 reference and it says that ip subnet-zero is enabled. Hopefully I have inserted enough padding for the url. (watch the wrap ) http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/ip_r /iprprt1/1rdipadr.htm#1020464 Having not worked with 12.2 I cant vouch that it has not be disabled, I just don't think it would. Call it an assumption, although I am aware of what assuming does :) The doc's also show, although less clear, that it appears to be enabled by default in 12.2. I don't have first hand knowledge of 12.2 so I am left to just trust the doc's... http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr _c/ipcprt1/1cfipadr.htm#1001056 I suspect that if Cisco was to test you on the 2^n vs. 2^n-2, that only one of them would be available. Thanks Larry -Original Message- From: Chuck [mailto:[EMAIL PROTECTED]] Sent: Saturday, July 13, 2002 1:28 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Larry, I'm only beating this dead horse for the CCNA/ beginner types on the list, who really do need to learn to distinguish between the function of a route summary versus the practicality of subnetting classful networks such that subnet zero becomes an issue. while I wouldn't bet the house on it, I suspect that even on Cisco tests, there would not be question about summarization where the subnet zero, all ones subnet count ( 2^n-2) would be the right answer. ( although I would not be surprised to see this in some of the study materials, given what I know about how quality control is valued with certain publishers. ) I was more concerned that it became a point of disagreement during the course of this thread, indicating that there were some who did not understand the why of things. Is ip subnet-zero enabled by default now? Which IOS release? Last I checked ( command reference for 12.2 ) the default was still disabled IP classless is now enabled by default, but not subnet-zero. this could have changed. the docs on CCO tend to be a bit behind reality. Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I don't think its unreachable. Cisco tests OTOH Most people use the 2^n-2 rule for determining the number of available/usable networks. The -2 is there because of the need to remove the network and broadcast subnet. I don't write the rules, I just question them :) I agree with you 100% that there are 16 subnets. I was trying to point out that those that we bringing up the fact that in the old world only 14 were available were not reading the question correctly. It didn't ask for usability, it asked for quantity. As I am sure you are aware, as you take more and more Cisco tests, it becomes important to clarify what they are actually asking for, not what would make sense for them to ask for... Its also important to note that IP subnet zero is still needed on Cisco eq for it to route/subnet properly, they just enabled it by default now... Thanks Larry -Original Message- From: Chuck [mailto:[EMAIL PROTECTED]] Sent: Friday, July 12, 2002 3:13 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] ah, but that is old world classful thinking. as per RFC 1812, effectively there is no such thing as subnet zero any longer. per that RFC, all routers SHOULD route to any address in the form of network:host, or network:subnet:host. subnet zero is a holdover from the old world. it is there because of the concern that there is still so much old world equipment out there. RFC 1812 is dated June 1995, and one wonders how long it takes in practical terms for all manufacturers and all software stack writers to get all their stuff up to standard.. not to mention how long it takes for the old stuff to be removed from production. hhhm. a brief look through ARIN seems to indicate that assignments are not made out of subnet zero space but that is still a different question. a summarization produces a single route where several existed before. if you see a summary 192.1.0.0/16, why would you think that 192.1.0.0/24 is unreachable? Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Just to jump in late on this, but... The question doesn't ask how many of those class C are usable, which would be dependant on subnet O, but instead the question was how many you would be able to summarize. A /20 would in fact summarize 16, 14 of which are useable without subnet zero... Thanks Larry -Original Message- From: Dain Deutschman [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 10, 2002 4:05 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:
RE: Class C summarization question [7:48367]
Just to jump in late on this, but... The question doesn't ask how many of those class C are usable, which would be dependant on subnet O, but instead the question was how many you would be able to summarize. A /20 would in fact summarize 16, 14 of which are useable without subnet zero... Thanks Larry -Original Message- From: Dain Deutschman [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 10, 2002 4:05 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Hey everyone, Thanks for all of your help. I have decided that 16 must be correct since it makes perfect sense and most of you back that up as well. I think the test question was just plain wrong. Anyway...I passed the CCNP Routing exam today so I'm pretty happy. : ) Groupstudy is a great learning resource. Thanks everyone. Dain. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48688t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
ah, but that is old world classful thinking. as per RFC 1812, effectively there is no such thing as subnet zero any longer. per that RFC, all routers SHOULD route to any address in the form of network:host, or network:subnet:host. subnet zero is a holdover from the old world. it is there because of the concern that there is still so much old world equipment out there. RFC 1812 is dated June 1995, and one wonders how long it takes in practical terms for all manufacturers and all software stack writers to get all their stuff up to standard.. not to mention how long it takes for the old stuff to be removed from production. hhhm. a brief look through ARIN seems to indicate that assignments are not made out of subnet zero space but that is still a different question. a summarization produces a single route where several existed before. if you see a summary 192.1.0.0/16, why would you think that 192.1.0.0/24 is unreachable? Chuck Roberts, Larry wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Just to jump in late on this, but... The question doesn't ask how many of those class C are usable, which would be dependant on subnet O, but instead the question was how many you would be able to summarize. A /20 would in fact summarize 16, 14 of which are useable without subnet zero... Thanks Larry -Original Message- From: Dain Deutschman [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 10, 2002 4:05 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Hey everyone, Thanks for all of your help. I have decided that 16 must be correct since it makes perfect sense and most of you back that up as well. I think the test question was just plain wrong. Anyway...I passed the CCNP Routing exam today so I'm pretty happy. : ) Groupstudy is a great learning resource. Thanks everyone. Dain. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48693t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Hey everyone, Thanks for all of your help. I have decided that 16 must be correct since it makes perfect sense and most of you back that up as well. I think the test question was just plain wrong. Anyway...I passed the CCNP Routing exam today so I'm pretty happy. : ) Groupstudy is a great learning resource. Thanks everyone. Dain. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48536t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
For a Cisco test the actuall answer would be 14. Unfortunately, for us, they don't take subnet zero into consideration for tests. So, if you have that question on the test answer 14, for the real-world it's 16. In other words, the answer to the BSCN question is wrong. Carl Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48379t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48389t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Firstly, 2 to the power of 4 is 16 (2x2x2x2). Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48393t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Bob Timmons wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I agree. A /20 can summarize 16 - /24 networks. AFAIK this is separate from zero-subnets and subnetting. Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48396t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
One of the choices in the question was 16but 14 was not a choice. Could it be that since 14 was not a choice that 8 was the closest thing since 16 is possibly wrong because of the 0 subnet? This seems a little off the wall to me butsometimes those cisco questions are off the wall. Dain. Bob Timmons wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Firstly, 2 to the power of 4 is 16 (2x2x2x2). Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48398t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
Bob, I would have to agree. With CIDR, in most cases you will get 16 usable subnets and 2 unusable addresses (the network and the broadcast). ex. 192.168.96.0 255.255.240.0 192.168.96.1 -- 192.168.111.254 all usable 192.168.96.0 network 192.168.111.255 broadcast I could see the question possibly not wanting the zero subnet if you used the following: 192.168.0.0 -- 192.168.15.255 where the 192.168.0.X network might be classified as unusable. This would give you 15 usable subnets... Tim CCIE 9015 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Bob Timmons Sent: Tuesday, July 09, 2002 7:28 AM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Firstly, 2 to the power of 4 is 16 (2x2x2x2). Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48403t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
If the choices are either 8 or 16, I'd definitely go with 16. 192.168.0.0/20 would be (for example): 192.168.0.1 to 192.168.15.254 Which is 16 total subnets. One of the choices in the question was 16but 14 was not a choice. Could it be that since 14 was not a choice that 8 was the closest thing since 16 is possibly wrong because of the 0 subnet? This seems a little off the wall to me butsometimes those cisco questions are off the wall. Dain. Bob Timmons wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Firstly, 2 to the power of 4 is 16 (2x2x2x2). Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48404t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
I was thinking of subnetting and not summarization, it was a little late. 16, not 14, is correct. Carl Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48405t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Dain Deutschman wrote: One of the choices in the question was 16but 14 was not a choice. Could it be that since 14 was not a choice that 8 was the closest thing since 16 is possibly wrong because of the 0 subnet? This seems a little off the wall to me butsometimes those cisco questions are off the wall. Dain. But couldn't you use that same logic and say 16 was the closest since 8 is wrong and 14 wasn't an answer? I still say 16 is the answer. Mike W. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48406t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
ah come on, guys, now you're all trying to outsmart yourselves. nothing in the RFC's regarding CIDR / summarization mentions a subnet zero why should it? that would defeat the purpose of CIDR/summarization. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... One of the choices in the question was 16but 14 was not a choice. Could it be that since 14 was not a choice that 8 was the closest thing since 16 is possibly wrong because of the 0 subnet? This seems a little off the wall to me butsometimes those cisco questions are off the wall. Dain. Bob Timmons wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Firstly, 2 to the power of 4 is 16 (2x2x2x2). Secondly, regarding Carl's post, would the answer be 14? I'm not sure the subnet-zero comes into play with CIDR. I was under the impression it was only relevant to subnetting as opposed to summarizing. Does anyone know for sure? I say 8. 2 to the power of 4 Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48413t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Dain, Just out of curiosity, who was the author of the test question? When I was studying for my CCNP I ran into several poorly written questions and others, like this one, that were just plain wrong. Also, are the people that think that 2 to the power of 4 equals 8 the same people that write to this list asking what they should study since they failed the CCNA on the first and second attempts? -- Brad A. Nixon CCNP, CCDA, MCP, CCSA Nothing is fool proof to a sufficiently talented fool. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48414t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
Ok I guess I deserved that. I was thinking of the 4th bit has a value of 8 in my head and forgot to add the values of the rest of the bits. -Original Message- From: Michael L. Williams [mailto:[EMAIL PROTECTED]] Sent: Monday, July 08, 2002 10:01 PM To: Andy Hoang; [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] Wow. According to my binary math, 4 bits = 16 combinations. 1 bit = 2 combinations (2^1 = 2) 2 bits = 4 combinations (2^2 = 4) 3 bits = 8 combinations (2^3 = 8) 4 bits = 16 combinations (2^4 = 16) Now. when converting from binary to decimal, the 4th bit (from the right) has a (decimal) value of 8 (2^[4-1]), but of course when you add the values of the bits from 4 down, you get 8+4+2+1 = 15 (thus giving 16 combinations, 0 through 15) (Too all that have read my posts in the past, now you know why I bitch up a storm when I hear someone encourage someone else to memorize subnetting charts and bitswapping charts instead of taking an hour and learning how binary actually works... geez) Mike W. - Original Message - From: Andy Hoang To: Michael L. Williams ; Sent: Monday, July 08, 2002 10:51 PM Subject: RE: Class C summarization question [7:48367] I would say 8 is correct. 4 bits make 8 combinations. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Monday, July 08, 2002 8:15 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48458t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Class C summarization question [7:48367]
I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48367t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48368t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
16 is the correct answer. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Dain Deutschman Sent: Monday, July 08, 2002 7:51 PM To: [EMAIL PROTECTED] Subject: Class C summarization question [7:48367] I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48369t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Thanks...it's good to know I'm not completely losing my mind. : ) Dain Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48370t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Class C summarization question [7:48367]
I would say 8 is correct. 4 bits make 8 combinations. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Monday, July 08, 2002 8:15 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48371t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Actually...4 bits makes 16 combinations( 2 to the power of 4 = 16 ) ( 4 positions with 2 possibilities per bit position ) Dain Andy Hoang wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I would say 8 is correct. 4 bits make 8 combinations. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Monday, July 08, 2002 8:15 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48372t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
Wow. According to my binary math, 4 bits = 16 combinations. 1 bit = 2 combinations (2^1 = 2) 2 bits = 4 combinations (2^2 = 4) 3 bits = 8 combinations (2^3 = 8) 4 bits = 16 combinations (2^4 = 16) Now. when converting from binary to decimal, the 4th bit (from the right) has a (decimal) value of 8 (2^[4-1]), but of course when you add the values of the bits from 4 down, you get 8+4+2+1 = 15 (thus giving 16 combinations, 0 through 15) (Too all that have read my posts in the past, now you know why I bitch up a storm when I hear someone encourage someone else to memorize subnetting charts and bitswapping charts instead of taking an hour and learning how binary actually works... geez) Mike W. - Original Message - From: Andy Hoang To: Michael L. Williams ; Sent: Monday, July 08, 2002 10:51 PM Subject: RE: Class C summarization question [7:48367] I would say 8 is correct. 4 bits make 8 combinations. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Monday, July 08, 2002 8:15 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48374t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Class C summarization question [7:48367]
FYI for who ever wants to knowA great website for learning subnetting ( actually learning the binary whys and hows instead of shortcuts ) is www.learntosubnet.com There are some great free resources...and very good explanations for those who are just starting to learn it. Dain Michael L. Williams wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Wow. According to my binary math, 4 bits = 16 combinations. 1 bit = 2 combinations (2^1 = 2) 2 bits = 4 combinations (2^2 = 4) 3 bits = 8 combinations (2^3 = 8) 4 bits = 16 combinations (2^4 = 16) Now. when converting from binary to decimal, the 4th bit (from the right) has a (decimal) value of 8 (2^[4-1]), but of course when you add the values of the bits from 4 down, you get 8+4+2+1 = 15 (thus giving 16 combinations, 0 through 15) (Too all that have read my posts in the past, now you know why I bitch up a storm when I hear someone encourage someone else to memorize subnetting charts and bitswapping charts instead of taking an hour and learning how binary actually works... geez) Mike W. - Original Message - From: Andy Hoang To: Michael L. Williams ; Sent: Monday, July 08, 2002 10:51 PM Subject: RE: Class C summarization question [7:48367] I would say 8 is correct. 4 bits make 8 combinations. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Michael L. Williams Sent: Monday, July 08, 2002 8:15 PM To: [EMAIL PROTECTED] Subject: Re: Class C summarization question [7:48367] I would say 16 as well. Mike W. Dain Deutschman wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I'm confused about a practice question for BSCN that I came across: Your routing tables are getting very large and you need to configure route summarization. How many class C internet addresses can you summarize with a /20 CIDR block? Answer: 8 Would it not be 16? Where am I going wrong? -- Dain Deutschman CNA, MCP, CCNA Data Communications Manager New Star Sales and Service, Inc. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=48376t=48367 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
