Let me break it down a little bit more: permit 0.0.0.0 255.255.254.255
The 255.255.254.255 is a wildcard mask....so in binary we have 11111111.11111111.11111110.11111111 This means we could care less about 31 out of the 32 bits in that IP address. The only thing we care about is that the least significant bit of the third octet is a 0, meaning anything with an even third octet is permitted. On Fri, Mar 5, 2010 at 3:01 PM, Joe Astorino <[email protected]> wrote: > You have it backwards. > > In wildcard masks 0 means "it must be" and 1 means " I don't care" > > > On Fri, Mar 5, 2010 at 2:33 PM, Mustafa Yadav <[email protected]>wrote: > >> I understood from here 255.255.254.255 is wildcard mask and normally it >> means 0.0.1.0 . >> >> 1 means I do care that bit and 0 means I do not care.Since 1 isd the least >> significant bit and in the network portion is zero ,having 0 in the that >> bit is a must. >> >> Is my understanding correct? >> >> On Fri, Mar 5, 2010 at 9:07 PM, Joe Astorino <[email protected]>wrote: >> >>> The access-list you have below will only allow networks with an even >>> third octet. Since it denies everything else, that would work. >>> >>> The logic here is that the least significant bit of the third octet must >>> be equal to a 0. Therefore, only evens are permitted since all even >>> networks end with a 0. >>> >>> On Fri, Mar 5, 2010 at 2:02 PM, Mustafa Yadav <[email protected] >>> > wrote: >>> >>>> hi all, >>>> I have read in one question asked do not want odd in third octet .I am >>>> not pretty sure about the answer but it was something like below.Can >>>> someone >>>> clarify the llogic behind it? >>>> >>>> access-list 1 permit 0.0.0.0 255.255.254.255 >>>> >>>> _______________________________________________ >>>> For more information regarding industry leading CCIE Lab training, >>>> please visit www.ipexpert.com >>>> >>>> >>> >>> >>> -- >>> Regards, >>> >>> Joe Astorino CCIE #24347 (R&S) >>> Sr. Technical Instructor - IPexpert >>> Mailto: [email protected] >>> Telephone: +1.810.326.1444 >>> Live Assistance, Please visit: www.ipexpert.com/chat >>> eFax: +1.810.454.0130 >>> >>> IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA >>> (R&S, Voice & Security), CCNP, CCVP, CCSP and CCIE (R&S, Voice, Security & >>> Service Provider) Certification Training with locations throughout the >>> United States, Europe and Australia. Be sure to check out our online >>> communities at www.ipexpert.com/communities and our public website at >>> www.ipexpert.com >>> >>> >>> >> > > > -- > Regards, > > Joe Astorino CCIE #24347 (R&S) > Sr. Technical Instructor - IPexpert > Mailto: [email protected] > Telephone: +1.810.326.1444 > Live Assistance, Please visit: www.ipexpert.com/chat > eFax: +1.810.454.0130 > > IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA (R&S, > Voice & Security), CCNP, CCVP, CCSP and CCIE (R&S, Voice, Security & Service > Provider) Certification Training with locations throughout the United > States, Europe and Australia. Be sure to check out our online communities at > www.ipexpert.com/communities and our public website at www.ipexpert.com > > > -- Regards, Joe Astorino CCIE #24347 (R&S) Sr. Technical Instructor - IPexpert Mailto: [email protected] Telephone: +1.810.326.1444 Live Assistance, Please visit: www.ipexpert.com/chat eFax: +1.810.454.0130 IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA (R&S, Voice & Security), CCNP, CCVP, CCSP and CCIE (R&S, Voice, Security & Service Provider) Certification Training with locations throughout the United States, Europe and Australia. Be sure to check out our online communities at www.ipexpert.com/communities and our public website at www.ipexpert.com
_______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
