Leading zeros in IPv4 address; is that a no-no by convention or standard?











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2
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I teach a class on a software product my company makes and I find that students frequently add leading zeros to a configuration page to have the software connect to our hardware. Leading zeros are problematic in our software, that's how and why this comes up.



I always explained that leading zeros were against "the standard" thinking that's what I had been taught. As I was submitting the bug report up the chain to my engineering department, I was unable to find an authoritative source for this (i.e. "The Standard"), but I did find some interesting and related information.



Are leading zeros bad because of convention, or do they go against the standard?



This was the closest I could find to a standard to not use leading zeros, but it's an expired draft of some kind:



Textual Representation of IPv4 and IPv6 Addresses



In the relevant section, it says:



3 Syntax and Semantics

3.1 IPv4 Dotted Octet Format

A 32-bit IPv4 address is divided into four octets. Each octet is
represented numerically in decimal, using the minimum possible number
of digits (leading zeroes are not used, except in the case of 0
itself). The four encoded octets are given most-significant first,
separated by period characters.

IPv4address = d8 "." d8 "." d8 "." d8

d8 = DIGIT ; 0-9
/ %x31-39 DIGIT ; 10-99
/ "1" 2DIGIT ; 100-199
/ "2" %x30-34 DIGIT ; 200-249
/ "25" %x30-35 ; 250-255


I also found the following articles discussing the phenomenon:



Ping and FTP Resolve IP Address with Leading Zero as Octal



Leading zeros in IP address can result in incorrect routing



Are IP addresses with and without leading zeroes the same?



Is there any documentation for omitting zeroes in dot-decimal notation of IPV4 addresses?










share|improve this question
























  • Thanks for the link edits. Normally I prefer to have the full text of the URL below the title, but I couldn't get that done, and then I couldn't have more than 2 links, so that really cleaned up the question.
    – YetAnotherRandomUser
    Jun 17 '15 at 16:29












  • In the end, it all comes down to the parser implementation, so most systems should like it fine, but some may not.... standards implementations are always like that.
    – Frank Thomas
    Jun 17 '15 at 16:45















up vote
2
down vote

favorite












I teach a class on a software product my company makes and I find that students frequently add leading zeros to a configuration page to have the software connect to our hardware. Leading zeros are problematic in our software, that's how and why this comes up.



I always explained that leading zeros were against "the standard" thinking that's what I had been taught. As I was submitting the bug report up the chain to my engineering department, I was unable to find an authoritative source for this (i.e. "The Standard"), but I did find some interesting and related information.



Are leading zeros bad because of convention, or do they go against the standard?



This was the closest I could find to a standard to not use leading zeros, but it's an expired draft of some kind:



Textual Representation of IPv4 and IPv6 Addresses



In the relevant section, it says:



3 Syntax and Semantics

3.1 IPv4 Dotted Octet Format

A 32-bit IPv4 address is divided into four octets. Each octet is
represented numerically in decimal, using the minimum possible number
of digits (leading zeroes are not used, except in the case of 0
itself). The four encoded octets are given most-significant first,
separated by period characters.

IPv4address = d8 "." d8 "." d8 "." d8

d8 = DIGIT ; 0-9
/ %x31-39 DIGIT ; 10-99
/ "1" 2DIGIT ; 100-199
/ "2" %x30-34 DIGIT ; 200-249
/ "25" %x30-35 ; 250-255


I also found the following articles discussing the phenomenon:



Ping and FTP Resolve IP Address with Leading Zero as Octal



Leading zeros in IP address can result in incorrect routing



Are IP addresses with and without leading zeroes the same?



Is there any documentation for omitting zeroes in dot-decimal notation of IPV4 addresses?










share|improve this question
























  • Thanks for the link edits. Normally I prefer to have the full text of the URL below the title, but I couldn't get that done, and then I couldn't have more than 2 links, so that really cleaned up the question.
    – YetAnotherRandomUser
    Jun 17 '15 at 16:29












  • In the end, it all comes down to the parser implementation, so most systems should like it fine, but some may not.... standards implementations are always like that.
    – Frank Thomas
    Jun 17 '15 at 16:45













up vote
2
down vote

favorite









up vote
2
down vote

favorite











I teach a class on a software product my company makes and I find that students frequently add leading zeros to a configuration page to have the software connect to our hardware. Leading zeros are problematic in our software, that's how and why this comes up.



I always explained that leading zeros were against "the standard" thinking that's what I had been taught. As I was submitting the bug report up the chain to my engineering department, I was unable to find an authoritative source for this (i.e. "The Standard"), but I did find some interesting and related information.



Are leading zeros bad because of convention, or do they go against the standard?



This was the closest I could find to a standard to not use leading zeros, but it's an expired draft of some kind:



Textual Representation of IPv4 and IPv6 Addresses



In the relevant section, it says:



3 Syntax and Semantics

3.1 IPv4 Dotted Octet Format

A 32-bit IPv4 address is divided into four octets. Each octet is
represented numerically in decimal, using the minimum possible number
of digits (leading zeroes are not used, except in the case of 0
itself). The four encoded octets are given most-significant first,
separated by period characters.

IPv4address = d8 "." d8 "." d8 "." d8

d8 = DIGIT ; 0-9
/ %x31-39 DIGIT ; 10-99
/ "1" 2DIGIT ; 100-199
/ "2" %x30-34 DIGIT ; 200-249
/ "25" %x30-35 ; 250-255


I also found the following articles discussing the phenomenon:



Ping and FTP Resolve IP Address with Leading Zero as Octal



Leading zeros in IP address can result in incorrect routing



Are IP addresses with and without leading zeroes the same?



Is there any documentation for omitting zeroes in dot-decimal notation of IPV4 addresses?










share|improve this question















I teach a class on a software product my company makes and I find that students frequently add leading zeros to a configuration page to have the software connect to our hardware. Leading zeros are problematic in our software, that's how and why this comes up.



I always explained that leading zeros were against "the standard" thinking that's what I had been taught. As I was submitting the bug report up the chain to my engineering department, I was unable to find an authoritative source for this (i.e. "The Standard"), but I did find some interesting and related information.



Are leading zeros bad because of convention, or do they go against the standard?



This was the closest I could find to a standard to not use leading zeros, but it's an expired draft of some kind:



Textual Representation of IPv4 and IPv6 Addresses



In the relevant section, it says:



3 Syntax and Semantics

3.1 IPv4 Dotted Octet Format

A 32-bit IPv4 address is divided into four octets. Each octet is
represented numerically in decimal, using the minimum possible number
of digits (leading zeroes are not used, except in the case of 0
itself). The four encoded octets are given most-significant first,
separated by period characters.

IPv4address = d8 "." d8 "." d8 "." d8

d8 = DIGIT ; 0-9
/ %x31-39 DIGIT ; 10-99
/ "1" 2DIGIT ; 100-199
/ "2" %x30-34 DIGIT ; 200-249
/ "25" %x30-35 ; 250-255


I also found the following articles discussing the phenomenon:



Ping and FTP Resolve IP Address with Leading Zero as Octal



Leading zeros in IP address can result in incorrect routing



Are IP addresses with and without leading zeroes the same?



Is there any documentation for omitting zeroes in dot-decimal notation of IPV4 addresses?







networking ip ipv4






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edited May 23 '17 at 12:41









Community

1




1










asked Jun 17 '15 at 16:10









YetAnotherRandomUser

84831230




84831230












  • Thanks for the link edits. Normally I prefer to have the full text of the URL below the title, but I couldn't get that done, and then I couldn't have more than 2 links, so that really cleaned up the question.
    – YetAnotherRandomUser
    Jun 17 '15 at 16:29












  • In the end, it all comes down to the parser implementation, so most systems should like it fine, but some may not.... standards implementations are always like that.
    – Frank Thomas
    Jun 17 '15 at 16:45


















  • Thanks for the link edits. Normally I prefer to have the full text of the URL below the title, but I couldn't get that done, and then I couldn't have more than 2 links, so that really cleaned up the question.
    – YetAnotherRandomUser
    Jun 17 '15 at 16:29












  • In the end, it all comes down to the parser implementation, so most systems should like it fine, but some may not.... standards implementations are always like that.
    – Frank Thomas
    Jun 17 '15 at 16:45
















Thanks for the link edits. Normally I prefer to have the full text of the URL below the title, but I couldn't get that done, and then I couldn't have more than 2 links, so that really cleaned up the question.
– YetAnotherRandomUser
Jun 17 '15 at 16:29






Thanks for the link edits. Normally I prefer to have the full text of the URL below the title, but I couldn't get that done, and then I couldn't have more than 2 links, so that really cleaned up the question.
– YetAnotherRandomUser
Jun 17 '15 at 16:29














In the end, it all comes down to the parser implementation, so most systems should like it fine, but some may not.... standards implementations are always like that.
– Frank Thomas
Jun 17 '15 at 16:45




In the end, it all comes down to the parser implementation, so most systems should like it fine, but some may not.... standards implementations are always like that.
– Frank Thomas
Jun 17 '15 at 16:45










4 Answers
4






active

oldest

votes

















up vote
5
down vote



accepted










There is no standard that demands an IPv4 address be expressed a certain way. That is, the RFC doesn't specify one and multiple formats are in widespread use. Most commonly, you'll see four octets as decimal numbers, but you may also see a single 8-digit hexadecimal number or even a single decimal number used instead. Though octal numbers are uncommon, many implementations accept those too.



This is the reason leading zeroes are usually avoided; the address could be ambiguous. '010.010.010.010' could be in a private range, but could also be Google's famous DNS server at '8.8.8.8'. Numbers that start with one leading zero and do not contain the digits 8 or 9 are often interpreted as octal.






share|improve this answer





















  • Which RFC are you referring to?
    – YetAnotherRandomUser
    Jun 17 '15 at 17:49






  • 1




    @allanonmage - In the context used. The only possability would be the RFC that cover IPv4
    – Ramhound
    Jun 17 '15 at 18:23






  • 1




    RFC 791, to be exact.
    – Marcks Thomas
    Jun 17 '15 at 20:48


















up vote
1
down vote













Ideally it shouldn't matter, as when it breaks down to binary/hex/whatever, the leading zeros shouldn't affect the end result.



Example: 192.168.1.1 to binary

192 = 11000000

168 = 10101000

1 = 00000001

1 = 00000001



Is the exact same as 192.168.001.001

192 = 11000000

168 = 10101000

001 = 00000001

001 = 00000001



See a previous SU answer here.






share|improve this answer























  • On some systems they might be interpreted differently, thus they should be avoided: superuser.com/a/857618/27205
    – Radu Maris
    Nov 4 '15 at 11:59


















up vote
0
down vote













0.0.0.0/8 is reserved for the local network (see RFC 6890 or for an easier read https://en.wikipedia.org/wiki/IPv4#Special-use_addresses).



Thus any address starting with 0 is valid but it's not the ip address of a particular machine.






share|improve this answer




























    up vote
    0
    down vote













    Let's go way back when some of us were pioneering the Internet world and look at this from an actual historical standpoint.



    Historical Fact: Many if not most of the early routers required (again: required) this exact format for IP address inputs: xxx.xxx.xxx.xxx



    What this means: Most folks who were around in the 1980s - 1990s configuring routers never gave a second thought to seeing IP addresses shown as: 192.168.001.010 After all, the padding with leading zeros was most often mandatory and never, ever, have I and I doubt most anyone else encountered a router, firewall, IP host of any kind really, that asked for Octal numbers.



    And so...



    001.001.001.001 = 1.1.1.1
    10.001.1.010 = 10.1.1.10 (inconsistently padding only some octets makes me sad)




    Why use padding now when almost year 2020 when most systems accept 1-3 base 10 characters in each octet rather than the old school 3? I can think of a reason that I encounter frequently:



    A sorted list of IP addresses in Excel.



    10.1.1.1
    10.100.254.50
    10.16.2.3
    10.3.129.44
    10.3.2.50


    ^ thats how Excel would sort these addresses (not numerically ordered!)



    But if you have a large list of IPs and wish to sort them: use padding zeros so that Excel provides this sorted list:



    010.001.001.001
    010.003.002.050
    010.003.129.044
    010.016.002.003
    010.100.254.050


    Now, if this list were 300+ addresses, lets say, and you wanted to view them in order, padding is your friend.



    Also, if these are in a database and a string sort was used to sort the list, padding is also you friend.






    share|improve this answer





















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      4 Answers
      4






      active

      oldest

      votes








      4 Answers
      4






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes








      up vote
      5
      down vote



      accepted










      There is no standard that demands an IPv4 address be expressed a certain way. That is, the RFC doesn't specify one and multiple formats are in widespread use. Most commonly, you'll see four octets as decimal numbers, but you may also see a single 8-digit hexadecimal number or even a single decimal number used instead. Though octal numbers are uncommon, many implementations accept those too.



      This is the reason leading zeroes are usually avoided; the address could be ambiguous. '010.010.010.010' could be in a private range, but could also be Google's famous DNS server at '8.8.8.8'. Numbers that start with one leading zero and do not contain the digits 8 or 9 are often interpreted as octal.






      share|improve this answer





















      • Which RFC are you referring to?
        – YetAnotherRandomUser
        Jun 17 '15 at 17:49






      • 1




        @allanonmage - In the context used. The only possability would be the RFC that cover IPv4
        – Ramhound
        Jun 17 '15 at 18:23






      • 1




        RFC 791, to be exact.
        – Marcks Thomas
        Jun 17 '15 at 20:48















      up vote
      5
      down vote



      accepted










      There is no standard that demands an IPv4 address be expressed a certain way. That is, the RFC doesn't specify one and multiple formats are in widespread use. Most commonly, you'll see four octets as decimal numbers, but you may also see a single 8-digit hexadecimal number or even a single decimal number used instead. Though octal numbers are uncommon, many implementations accept those too.



      This is the reason leading zeroes are usually avoided; the address could be ambiguous. '010.010.010.010' could be in a private range, but could also be Google's famous DNS server at '8.8.8.8'. Numbers that start with one leading zero and do not contain the digits 8 or 9 are often interpreted as octal.






      share|improve this answer





















      • Which RFC are you referring to?
        – YetAnotherRandomUser
        Jun 17 '15 at 17:49






      • 1




        @allanonmage - In the context used. The only possability would be the RFC that cover IPv4
        – Ramhound
        Jun 17 '15 at 18:23






      • 1




        RFC 791, to be exact.
        – Marcks Thomas
        Jun 17 '15 at 20:48













      up vote
      5
      down vote



      accepted







      up vote
      5
      down vote



      accepted






      There is no standard that demands an IPv4 address be expressed a certain way. That is, the RFC doesn't specify one and multiple formats are in widespread use. Most commonly, you'll see four octets as decimal numbers, but you may also see a single 8-digit hexadecimal number or even a single decimal number used instead. Though octal numbers are uncommon, many implementations accept those too.



      This is the reason leading zeroes are usually avoided; the address could be ambiguous. '010.010.010.010' could be in a private range, but could also be Google's famous DNS server at '8.8.8.8'. Numbers that start with one leading zero and do not contain the digits 8 or 9 are often interpreted as octal.






      share|improve this answer












      There is no standard that demands an IPv4 address be expressed a certain way. That is, the RFC doesn't specify one and multiple formats are in widespread use. Most commonly, you'll see four octets as decimal numbers, but you may also see a single 8-digit hexadecimal number or even a single decimal number used instead. Though octal numbers are uncommon, many implementations accept those too.



      This is the reason leading zeroes are usually avoided; the address could be ambiguous. '010.010.010.010' could be in a private range, but could also be Google's famous DNS server at '8.8.8.8'. Numbers that start with one leading zero and do not contain the digits 8 or 9 are often interpreted as octal.







      share|improve this answer












      share|improve this answer



      share|improve this answer










      answered Jun 17 '15 at 17:07









      Marcks Thomas

      5,47311736




      5,47311736












      • Which RFC are you referring to?
        – YetAnotherRandomUser
        Jun 17 '15 at 17:49






      • 1




        @allanonmage - In the context used. The only possability would be the RFC that cover IPv4
        – Ramhound
        Jun 17 '15 at 18:23






      • 1




        RFC 791, to be exact.
        – Marcks Thomas
        Jun 17 '15 at 20:48


















      • Which RFC are you referring to?
        – YetAnotherRandomUser
        Jun 17 '15 at 17:49






      • 1




        @allanonmage - In the context used. The only possability would be the RFC that cover IPv4
        – Ramhound
        Jun 17 '15 at 18:23






      • 1




        RFC 791, to be exact.
        – Marcks Thomas
        Jun 17 '15 at 20:48
















      Which RFC are you referring to?
      – YetAnotherRandomUser
      Jun 17 '15 at 17:49




      Which RFC are you referring to?
      – YetAnotherRandomUser
      Jun 17 '15 at 17:49




      1




      1




      @allanonmage - In the context used. The only possability would be the RFC that cover IPv4
      – Ramhound
      Jun 17 '15 at 18:23




      @allanonmage - In the context used. The only possability would be the RFC that cover IPv4
      – Ramhound
      Jun 17 '15 at 18:23




      1




      1




      RFC 791, to be exact.
      – Marcks Thomas
      Jun 17 '15 at 20:48




      RFC 791, to be exact.
      – Marcks Thomas
      Jun 17 '15 at 20:48












      up vote
      1
      down vote













      Ideally it shouldn't matter, as when it breaks down to binary/hex/whatever, the leading zeros shouldn't affect the end result.



      Example: 192.168.1.1 to binary

      192 = 11000000

      168 = 10101000

      1 = 00000001

      1 = 00000001



      Is the exact same as 192.168.001.001

      192 = 11000000

      168 = 10101000

      001 = 00000001

      001 = 00000001



      See a previous SU answer here.






      share|improve this answer























      • On some systems they might be interpreted differently, thus they should be avoided: superuser.com/a/857618/27205
        – Radu Maris
        Nov 4 '15 at 11:59















      up vote
      1
      down vote













      Ideally it shouldn't matter, as when it breaks down to binary/hex/whatever, the leading zeros shouldn't affect the end result.



      Example: 192.168.1.1 to binary

      192 = 11000000

      168 = 10101000

      1 = 00000001

      1 = 00000001



      Is the exact same as 192.168.001.001

      192 = 11000000

      168 = 10101000

      001 = 00000001

      001 = 00000001



      See a previous SU answer here.






      share|improve this answer























      • On some systems they might be interpreted differently, thus they should be avoided: superuser.com/a/857618/27205
        – Radu Maris
        Nov 4 '15 at 11:59













      up vote
      1
      down vote










      up vote
      1
      down vote









      Ideally it shouldn't matter, as when it breaks down to binary/hex/whatever, the leading zeros shouldn't affect the end result.



      Example: 192.168.1.1 to binary

      192 = 11000000

      168 = 10101000

      1 = 00000001

      1 = 00000001



      Is the exact same as 192.168.001.001

      192 = 11000000

      168 = 10101000

      001 = 00000001

      001 = 00000001



      See a previous SU answer here.






      share|improve this answer














      Ideally it shouldn't matter, as when it breaks down to binary/hex/whatever, the leading zeros shouldn't affect the end result.



      Example: 192.168.1.1 to binary

      192 = 11000000

      168 = 10101000

      1 = 00000001

      1 = 00000001



      Is the exact same as 192.168.001.001

      192 = 11000000

      168 = 10101000

      001 = 00000001

      001 = 00000001



      See a previous SU answer here.







      share|improve this answer














      share|improve this answer



      share|improve this answer








      edited Mar 20 '17 at 10:17









      Community

      1




      1










      answered Jun 17 '15 at 16:42









      kazoni

      584212




      584212












      • On some systems they might be interpreted differently, thus they should be avoided: superuser.com/a/857618/27205
        – Radu Maris
        Nov 4 '15 at 11:59


















      • On some systems they might be interpreted differently, thus they should be avoided: superuser.com/a/857618/27205
        – Radu Maris
        Nov 4 '15 at 11:59
















      On some systems they might be interpreted differently, thus they should be avoided: superuser.com/a/857618/27205
      – Radu Maris
      Nov 4 '15 at 11:59




      On some systems they might be interpreted differently, thus they should be avoided: superuser.com/a/857618/27205
      – Radu Maris
      Nov 4 '15 at 11:59










      up vote
      0
      down vote













      0.0.0.0/8 is reserved for the local network (see RFC 6890 or for an easier read https://en.wikipedia.org/wiki/IPv4#Special-use_addresses).



      Thus any address starting with 0 is valid but it's not the ip address of a particular machine.






      share|improve this answer

























        up vote
        0
        down vote













        0.0.0.0/8 is reserved for the local network (see RFC 6890 or for an easier read https://en.wikipedia.org/wiki/IPv4#Special-use_addresses).



        Thus any address starting with 0 is valid but it's not the ip address of a particular machine.






        share|improve this answer























          up vote
          0
          down vote










          up vote
          0
          down vote









          0.0.0.0/8 is reserved for the local network (see RFC 6890 or for an easier read https://en.wikipedia.org/wiki/IPv4#Special-use_addresses).



          Thus any address starting with 0 is valid but it's not the ip address of a particular machine.






          share|improve this answer












          0.0.0.0/8 is reserved for the local network (see RFC 6890 or for an easier read https://en.wikipedia.org/wiki/IPv4#Special-use_addresses).



          Thus any address starting with 0 is valid but it's not the ip address of a particular machine.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Jun 17 '15 at 16:55









          Jason Parachoniak

          1




          1






















              up vote
              0
              down vote













              Let's go way back when some of us were pioneering the Internet world and look at this from an actual historical standpoint.



              Historical Fact: Many if not most of the early routers required (again: required) this exact format for IP address inputs: xxx.xxx.xxx.xxx



              What this means: Most folks who were around in the 1980s - 1990s configuring routers never gave a second thought to seeing IP addresses shown as: 192.168.001.010 After all, the padding with leading zeros was most often mandatory and never, ever, have I and I doubt most anyone else encountered a router, firewall, IP host of any kind really, that asked for Octal numbers.



              And so...



              001.001.001.001 = 1.1.1.1
              10.001.1.010 = 10.1.1.10 (inconsistently padding only some octets makes me sad)




              Why use padding now when almost year 2020 when most systems accept 1-3 base 10 characters in each octet rather than the old school 3? I can think of a reason that I encounter frequently:



              A sorted list of IP addresses in Excel.



              10.1.1.1
              10.100.254.50
              10.16.2.3
              10.3.129.44
              10.3.2.50


              ^ thats how Excel would sort these addresses (not numerically ordered!)



              But if you have a large list of IPs and wish to sort them: use padding zeros so that Excel provides this sorted list:



              010.001.001.001
              010.003.002.050
              010.003.129.044
              010.016.002.003
              010.100.254.050


              Now, if this list were 300+ addresses, lets say, and you wanted to view them in order, padding is your friend.



              Also, if these are in a database and a string sort was used to sort the list, padding is also you friend.






              share|improve this answer

























                up vote
                0
                down vote













                Let's go way back when some of us were pioneering the Internet world and look at this from an actual historical standpoint.



                Historical Fact: Many if not most of the early routers required (again: required) this exact format for IP address inputs: xxx.xxx.xxx.xxx



                What this means: Most folks who were around in the 1980s - 1990s configuring routers never gave a second thought to seeing IP addresses shown as: 192.168.001.010 After all, the padding with leading zeros was most often mandatory and never, ever, have I and I doubt most anyone else encountered a router, firewall, IP host of any kind really, that asked for Octal numbers.



                And so...



                001.001.001.001 = 1.1.1.1
                10.001.1.010 = 10.1.1.10 (inconsistently padding only some octets makes me sad)




                Why use padding now when almost year 2020 when most systems accept 1-3 base 10 characters in each octet rather than the old school 3? I can think of a reason that I encounter frequently:



                A sorted list of IP addresses in Excel.



                10.1.1.1
                10.100.254.50
                10.16.2.3
                10.3.129.44
                10.3.2.50


                ^ thats how Excel would sort these addresses (not numerically ordered!)



                But if you have a large list of IPs and wish to sort them: use padding zeros so that Excel provides this sorted list:



                010.001.001.001
                010.003.002.050
                010.003.129.044
                010.016.002.003
                010.100.254.050


                Now, if this list were 300+ addresses, lets say, and you wanted to view them in order, padding is your friend.



                Also, if these are in a database and a string sort was used to sort the list, padding is also you friend.






                share|improve this answer























                  up vote
                  0
                  down vote










                  up vote
                  0
                  down vote









                  Let's go way back when some of us were pioneering the Internet world and look at this from an actual historical standpoint.



                  Historical Fact: Many if not most of the early routers required (again: required) this exact format for IP address inputs: xxx.xxx.xxx.xxx



                  What this means: Most folks who were around in the 1980s - 1990s configuring routers never gave a second thought to seeing IP addresses shown as: 192.168.001.010 After all, the padding with leading zeros was most often mandatory and never, ever, have I and I doubt most anyone else encountered a router, firewall, IP host of any kind really, that asked for Octal numbers.



                  And so...



                  001.001.001.001 = 1.1.1.1
                  10.001.1.010 = 10.1.1.10 (inconsistently padding only some octets makes me sad)




                  Why use padding now when almost year 2020 when most systems accept 1-3 base 10 characters in each octet rather than the old school 3? I can think of a reason that I encounter frequently:



                  A sorted list of IP addresses in Excel.



                  10.1.1.1
                  10.100.254.50
                  10.16.2.3
                  10.3.129.44
                  10.3.2.50


                  ^ thats how Excel would sort these addresses (not numerically ordered!)



                  But if you have a large list of IPs and wish to sort them: use padding zeros so that Excel provides this sorted list:



                  010.001.001.001
                  010.003.002.050
                  010.003.129.044
                  010.016.002.003
                  010.100.254.050


                  Now, if this list were 300+ addresses, lets say, and you wanted to view them in order, padding is your friend.



                  Also, if these are in a database and a string sort was used to sort the list, padding is also you friend.






                  share|improve this answer












                  Let's go way back when some of us were pioneering the Internet world and look at this from an actual historical standpoint.



                  Historical Fact: Many if not most of the early routers required (again: required) this exact format for IP address inputs: xxx.xxx.xxx.xxx



                  What this means: Most folks who were around in the 1980s - 1990s configuring routers never gave a second thought to seeing IP addresses shown as: 192.168.001.010 After all, the padding with leading zeros was most often mandatory and never, ever, have I and I doubt most anyone else encountered a router, firewall, IP host of any kind really, that asked for Octal numbers.



                  And so...



                  001.001.001.001 = 1.1.1.1
                  10.001.1.010 = 10.1.1.10 (inconsistently padding only some octets makes me sad)




                  Why use padding now when almost year 2020 when most systems accept 1-3 base 10 characters in each octet rather than the old school 3? I can think of a reason that I encounter frequently:



                  A sorted list of IP addresses in Excel.



                  10.1.1.1
                  10.100.254.50
                  10.16.2.3
                  10.3.129.44
                  10.3.2.50


                  ^ thats how Excel would sort these addresses (not numerically ordered!)



                  But if you have a large list of IPs and wish to sort them: use padding zeros so that Excel provides this sorted list:



                  010.001.001.001
                  010.003.002.050
                  010.003.129.044
                  010.016.002.003
                  010.100.254.050


                  Now, if this list were 300+ addresses, lets say, and you wanted to view them in order, padding is your friend.



                  Also, if these are in a database and a string sort was used to sort the list, padding is also you friend.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Nov 21 at 14:23









                  shaggy1966

                  11




                  11






























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