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Is X.Y.Z.0 a valid IP address?
What is the purpose of the “Network IP address”, why can it not normally be used?Most popular misconceptions about networkingIs it valid to have part of an IPv4 address set to zero?What is the network address (x.x.x.0) used for?Access to local dhcp server via sshWin 7 Netbook refuses to ping JetDirect card (all other PCs work)How does IPv4 Subnetting Work?Cisco, How to do a subnetting scheme using VLSM and RIP-2?Networking Question - What is a VALID Subnet Address?Why couldn't MAC addresses be used instead of IPv4|6 for networking?How does IPv6 subnetting work and how does it differ from IPv4 subnetting?Customer site is out of IP addresses, they want to go from /24 to /12 netmask… Bad idea?First and last IP address of the network 192.168.176.0/23 (subnet 23)Enlarge IP Network Address SpaceAnomany while creating 128 subnets for class C IP addressWould IP addresses with the same first 3 octets necessarily be from the same origin?
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty height:90px;width:728px;box-sizing:border-box;
Are IP addresses with a 0 in the last octet valid?
10.6.43.0
In my case, I have the the following netmask
255.255.252.0
What about a 0 for the other octets?
networking tcpip subnet
edited Jul 18 '09 at 14:53
splattne
25.8k1892144
asked May 21 '09 at 20:39
Alan HAlan H
1,48931616
add a comment |
Are IP addresses with a 0 in the last octet valid?
10.6.43.0
In my case, I have the the following netmask
255.255.252.0
What about a 0 for the other octets?
networking tcpip subnet
edited Jul 18 '09 at 14:53
splattne
25.8k1892144
asked May 21 '09 at 20:39
Alan HAlan H
1,48931616
12
others have answered, but we run /23s in our DHCP ranges, meaning that the middle .255 and .0 addresses of the two /24s get assigned to clients. Works fine. Sometimes "knowledgeable" users freak out a little thinking they've pulled an invalid IP, but from a networking POV it works fine.
– jj33
May 21 '09 at 21:26
1
See Also: What is the network address X.Y.Z.0 used for?
– voretaq7
Nov 19 '12 at 23:07
add a comment |
Are IP addresses with a 0 in the last octet valid?
10.6.43.0
In my case, I have the the following netmask
255.255.252.0
What about a 0 for the other octets?
networking tcpip subnet
edited Jul 18 '09 at 14:53
splattne
25.8k1892144
asked May 21 '09 at 20:39
Alan HAlan H
1,48931616
Are IP addresses with a 0 in the last octet valid?
10.6.43.0
In my case, I have the the following netmask
255.255.252.0
What about a 0 for the other octets?
networking tcpip subnet
networking tcpip subnet
edited Jul 18 '09 at 14:53
splattne
25.8k1892144
asked May 21 '09 at 20:39
Alan HAlan H
1,48931616
edited Jul 18 '09 at 14:53
splattne
25.8k1892144
asked May 21 '09 at 20:39
Alan HAlan H
1,48931616
edited Jul 18 '09 at 14:53
splattne
25.8k1892144
edited Jul 18 '09 at 14:53
splattne
25.8k1892144
edited Jul 18 '09 at 14:53
splattne
25.8k1892144
25.8k1892144
asked May 21 '09 at 20:39
Alan HAlan H
1,48931616
asked May 21 '09 at 20:39
Alan HAlan H
1,48931616
asked May 21 '09 at 20:39
Alan HAlan H
1,48931616
1,48931616
12
others have answered, but we run /23s in our DHCP ranges, meaning that the middle .255 and .0 addresses of the two /24s get assigned to clients. Works fine. Sometimes "knowledgeable" users freak out a little thinking they've pulled an invalid IP, but from a networking POV it works fine.
– jj33
May 21 '09 at 21:26
1
See Also: What is the network address X.Y.Z.0 used for?
– voretaq7
Nov 19 '12 at 23:07
add a comment |
12
others have answered, but we run /23s in our DHCP ranges, meaning that the middle .255 and .0 addresses of the two /24s get assigned to clients. Works fine. Sometimes "knowledgeable" users freak out a little thinking they've pulled an invalid IP, but from a networking POV it works fine.
– jj33
May 21 '09 at 21:26
1
See Also: What is the network address X.Y.Z.0 used for?
– voretaq7
Nov 19 '12 at 23:07
12
12
others have answered, but we run /23s in our DHCP ranges, meaning that the middle .255 and .0 addresses of the two /24s get assigned to clients. Works fine. Sometimes "knowledgeable" users freak out a little thinking they've pulled an invalid IP, but from a networking POV it works fine.
– jj33
May 21 '09 at 21:26
others have answered, but we run /23s in our DHCP ranges, meaning that the middle .255 and .0 addresses of the two /24s get assigned to clients. Works fine. Sometimes "knowledgeable" users freak out a little thinking they've pulled an invalid IP, but from a networking POV it works fine.
– jj33
May 21 '09 at 21:26
1
1
See Also: What is the network address X.Y.Z.0 used for?
– voretaq7
Nov 19 '12 at 23:07
See Also: What is the network address X.Y.Z.0 used for?
– voretaq7
Nov 19 '12 at 23:07
add a comment |
6 Answers
6
active
oldest
votes
It depends on the subnet of the IP address in question. In general, the first and last addresses in a subnet are used as the network identifier and broadcast address, respectively. All other addresses in the subnet can be assigned to hosts on that subnet.
For example, IP addresses of networks with subnet masks of at least 24 bits ending in .0 or .255 can never be assigned to hosts. Such "last" addresses of a subnet are considered "broadcast" addresses and all hosts on the corresponding subnet will respond to it.
Theoretically, there could be situations where you can assign an address ending in .0: for example, if you have a subnet like 192.168.0.0/255.255.0.0, you are allowed to assign a host the address 192.168.1.0. It could create confusion though, so it's not a very common practice.
In your example
10.6.43.0 with subnet 255.255.252.0 (22 bit subnet mask)
means subnet ID 10.6.40.0, a host address range from 10.6.40.1 to 10.6.43.254 and a broadcast address 10.6.43.255. So in theory, your example 10.6.43.0 would be allowed as a valid host address.
answered May 21 '09 at 20:41
splattnesplattne
25.8k1892144
4
One addition. In the past I have had to deal with some older software that had problems with using a .0 address in places where it was a perfectly legal thing to do.
– Zoredache
May 21 '09 at 22:56
And no answer to this question would be complete without a reference to the CIDR RFCs: RFC1518 and RFC1519 which define all this.
– pjz
May 22 '09 at 2:42
16
RFC 1519 is obsolete for a long time. The current version is RFC 4632.
– bortzmeyer
May 22 '09 at 6:11
Just got assigned a dot zero by an Amazon EC2 instance. They are sure maximising the IP's they have.
– Matt
Jun 5 '17 at 20:38
@bortzmeyer, RFC 4632 is simply a BEST CURRENT PRACTICE, while RFC 1519 is a standards track RFC.
– Ron Maupin
May 27 at 3:39
add a comment |
answer to your question depends on the netmask. in general statement 'IP addresses ending in .0 or .255 is invalid' is false. take 10.0.1.0/23 - it's valid ip address.
also 10.6.43.0/255.255.252.0 aka 10.6.43.0/22 is valid.
that was the theory. most reasonable network devices [ including linux servers, windows boxes, cisco / hp / etc ] will work fine with such address, but i've seen dlink and other low-end network appliance [ routers, access points ] not accepting such addresses.
answered May 21 '09 at 20:45
pQdpQd
25.8k35597
add a comment |
I found this, which claims that it is valid, depending on your subnet mask.
http://en.wikipedia.org/wiki/IPv4#Addresses_ending_in_0_or_255
answered May 21 '09 at 21:24
Alan HAlan H
1,48931616
add a comment |
I'd like to add a bit about 0 for the other octets:
This one is easy: it's no problem at all, as the fairly common private network address 192.168.0.1 shows.
Of course an even more obvious example would be 127.0.0.1.
edited Aug 22 '09 at 9:39
splattne
25.8k1892144
answered Jul 4 '09 at 15:44
Joachim SauerJoachim Sauer
741316
1
-1 for obvious...
– Jon Rhoades
Aug 22 '09 at 11:36
5
+1 for pointing out the obvious
– just somebody
Oct 1 '12 at 9:47
The question isn't asking about zeroes in the other octets.
– slang
Aug 31 '17 at 16:27
2
@slang: Except it literally asks about exactly that in the last sentence.
– Joachim Sauer
Aug 31 '17 at 16:28
add a comment |
I have run into problems with remote networks denying IP addresses from my network if they ended with 0 (or 255) and they were from the class C range, since anything ending with 0 would be an invalid class C network.
This was a few years ago; I don't know if anyone still blocks addresses like that or not.
answered Jun 27 '09 at 12:26
Josh KelleyJosh Kelley
5331416
That just sounds like your firewall/software is a bit daft ;)
– nixgeek
Jul 4 '09 at 15:51
Every IP address on my network except .0 or .255 could access every site, IP addresses ending in .0 and .255 could access 95% of sites, but there were two or three completely different sites that they couldn't access. If it was my firewall/software, I sure couldn't figure out how.
– Josh Kelley
Jul 4 '09 at 17:22
1
These must be using firewalls configured by the same kind of people who block all ICMP and end up breaking PMTUD, or block all "invalid" TCP flags and end up breaking ECN.
– CesarB
Jul 5 '09 at 0:11
Microsoft servers allegedly do it even today. No Windows Update for you. But Microsoft has been known to break the rules since forever.
– Zdenek
Feb 20 '16 at 12:15
add a comment |
Just something I found that's probably noteworthy:
If you're running R-fx networks' APF script for iptables, it drops all traffic to 0.0.0.255
We had a BT customer with an address ending in .255 with a prefix of /21 .. Technically a valid IP address, however the guys at R-fx networks think there is cause for dropping packets for these addresses.
answered Jan 17 '11 at 14:10
SqueebSqueeb
122111
they are choosing to drop packets to 0.0.0.255 most likely for security purposes. 1) DOS attacks can happen by leveraging the power of a broadcast packet and 2) to completely privatize the network so no hosts can broadcast. see en.wikipedia.org/wiki/Broadcast_traffic#Security
– zamnuts
Jul 3 '13 at 23:41
add a comment |
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6 Answers
6
active
oldest
votes
6 Answers
6
active
oldest
votes
active
oldest
votes
active
oldest
votes
It depends on the subnet of the IP address in question. In general, the first and last addresses in a subnet are used as the network identifier and broadcast address, respectively. All other addresses in the subnet can be assigned to hosts on that subnet.
For example, IP addresses of networks with subnet masks of at least 24 bits ending in .0 or .255 can never be assigned to hosts. Such "last" addresses of a subnet are considered "broadcast" addresses and all hosts on the corresponding subnet will respond to it.
Theoretically, there could be situations where you can assign an address ending in .0: for example, if you have a subnet like 192.168.0.0/255.255.0.0, you are allowed to assign a host the address 192.168.1.0. It could create confusion though, so it's not a very common practice.
In your example
10.6.43.0 with subnet 255.255.252.0 (22 bit subnet mask)
means subnet ID 10.6.40.0, a host address range from 10.6.40.1 to 10.6.43.254 and a broadcast address 10.6.43.255. So in theory, your example 10.6.43.0 would be allowed as a valid host address.
answered May 21 '09 at 20:41
splattnesplattne
25.8k1892144
4
One addition. In the past I have had to deal with some older software that had problems with using a .0 address in places where it was a perfectly legal thing to do.
– Zoredache
May 21 '09 at 22:56
And no answer to this question would be complete without a reference to the CIDR RFCs: RFC1518 and RFC1519 which define all this.
– pjz
May 22 '09 at 2:42
16
RFC 1519 is obsolete for a long time. The current version is RFC 4632.
– bortzmeyer
May 22 '09 at 6:11
Just got assigned a dot zero by an Amazon EC2 instance. They are sure maximising the IP's they have.
– Matt
Jun 5 '17 at 20:38
@bortzmeyer, RFC 4632 is simply a BEST CURRENT PRACTICE, while RFC 1519 is a standards track RFC.
– Ron Maupin
May 27 at 3:39
add a comment |
It depends on the subnet of the IP address in question. In general, the first and last addresses in a subnet are used as the network identifier and broadcast address, respectively. All other addresses in the subnet can be assigned to hosts on that subnet.
For example, IP addresses of networks with subnet masks of at least 24 bits ending in .0 or .255 can never be assigned to hosts. Such "last" addresses of a subnet are considered "broadcast" addresses and all hosts on the corresponding subnet will respond to it.
Theoretically, there could be situations where you can assign an address ending in .0: for example, if you have a subnet like 192.168.0.0/255.255.0.0, you are allowed to assign a host the address 192.168.1.0. It could create confusion though, so it's not a very common practice.
In your example
10.6.43.0 with subnet 255.255.252.0 (22 bit subnet mask)
means subnet ID 10.6.40.0, a host address range from 10.6.40.1 to 10.6.43.254 and a broadcast address 10.6.43.255. So in theory, your example 10.6.43.0 would be allowed as a valid host address.
answered May 21 '09 at 20:41
splattnesplattne
25.8k1892144
4
One addition. In the past I have had to deal with some older software that had problems with using a .0 address in places where it was a perfectly legal thing to do.
– Zoredache
May 21 '09 at 22:56
And no answer to this question would be complete without a reference to the CIDR RFCs: RFC1518 and RFC1519 which define all this.
– pjz
May 22 '09 at 2:42
16
RFC 1519 is obsolete for a long time. The current version is RFC 4632.
– bortzmeyer
May 22 '09 at 6:11
Just got assigned a dot zero by an Amazon EC2 instance. They are sure maximising the IP's they have.
– Matt
Jun 5 '17 at 20:38
@bortzmeyer, RFC 4632 is simply a BEST CURRENT PRACTICE, while RFC 1519 is a standards track RFC.
– Ron Maupin
May 27 at 3:39
add a comment |
It depends on the subnet of the IP address in question. In general, the first and last addresses in a subnet are used as the network identifier and broadcast address, respectively. All other addresses in the subnet can be assigned to hosts on that subnet.
For example, IP addresses of networks with subnet masks of at least 24 bits ending in .0 or .255 can never be assigned to hosts. Such "last" addresses of a subnet are considered "broadcast" addresses and all hosts on the corresponding subnet will respond to it.
Theoretically, there could be situations where you can assign an address ending in .0: for example, if you have a subnet like 192.168.0.0/255.255.0.0, you are allowed to assign a host the address 192.168.1.0. It could create confusion though, so it's not a very common practice.
In your example
10.6.43.0 with subnet 255.255.252.0 (22 bit subnet mask)
means subnet ID 10.6.40.0, a host address range from 10.6.40.1 to 10.6.43.254 and a broadcast address 10.6.43.255. So in theory, your example 10.6.43.0 would be allowed as a valid host address.
answered May 21 '09 at 20:41
splattnesplattne
25.8k1892144
It depends on the subnet of the IP address in question. In general, the first and last addresses in a subnet are used as the network identifier and broadcast address, respectively. All other addresses in the subnet can be assigned to hosts on that subnet.
For example, IP addresses of networks with subnet masks of at least 24 bits ending in .0 or .255 can never be assigned to hosts. Such "last" addresses of a subnet are considered "broadcast" addresses and all hosts on the corresponding subnet will respond to it.
Theoretically, there could be situations where you can assign an address ending in .0: for example, if you have a subnet like 192.168.0.0/255.255.0.0, you are allowed to assign a host the address 192.168.1.0. It could create confusion though, so it's not a very common practice.
In your example
10.6.43.0 with subnet 255.255.252.0 (22 bit subnet mask)
means subnet ID 10.6.40.0, a host address range from 10.6.40.1 to 10.6.43.254 and a broadcast address 10.6.43.255. So in theory, your example 10.6.43.0 would be allowed as a valid host address.
answered May 21 '09 at 20:41
splattnesplattne
25.8k1892144
edited Jun 27 '09 at 11:13
answered May 21 '09 at 20:41
splattnesplattne
25.8k1892144
answered May 21 '09 at 20:41
splattnesplattne
25.8k1892144
answered May 21 '09 at 20:41
splattnesplattne
25.8k1892144
25.8k1892144
4
One addition. In the past I have had to deal with some older software that had problems with using a .0 address in places where it was a perfectly legal thing to do.
– Zoredache
May 21 '09 at 22:56
And no answer to this question would be complete without a reference to the CIDR RFCs: RFC1518 and RFC1519 which define all this.
– pjz
May 22 '09 at 2:42
16
RFC 1519 is obsolete for a long time. The current version is RFC 4632.
– bortzmeyer
May 22 '09 at 6:11
Just got assigned a dot zero by an Amazon EC2 instance. They are sure maximising the IP's they have.
– Matt
Jun 5 '17 at 20:38
@bortzmeyer, RFC 4632 is simply a BEST CURRENT PRACTICE, while RFC 1519 is a standards track RFC.
– Ron Maupin
May 27 at 3:39
add a comment |
4
One addition. In the past I have had to deal with some older software that had problems with using a .0 address in places where it was a perfectly legal thing to do.
– Zoredache
May 21 '09 at 22:56
And no answer to this question would be complete without a reference to the CIDR RFCs: RFC1518 and RFC1519 which define all this.
– pjz
May 22 '09 at 2:42
16
RFC 1519 is obsolete for a long time. The current version is RFC 4632.
– bortzmeyer
May 22 '09 at 6:11
Just got assigned a dot zero by an Amazon EC2 instance. They are sure maximising the IP's they have.
– Matt
Jun 5 '17 at 20:38
@bortzmeyer, RFC 4632 is simply a BEST CURRENT PRACTICE, while RFC 1519 is a standards track RFC.
– Ron Maupin
May 27 at 3:39
4
4
One addition. In the past I have had to deal with some older software that had problems with using a .0 address in places where it was a perfectly legal thing to do.
– Zoredache
May 21 '09 at 22:56
One addition. In the past I have had to deal with some older software that had problems with using a .0 address in places where it was a perfectly legal thing to do.
– Zoredache
May 21 '09 at 22:56
And no answer to this question would be complete without a reference to the CIDR RFCs: RFC1518 and RFC1519 which define all this.
– pjz
May 22 '09 at 2:42
And no answer to this question would be complete without a reference to the CIDR RFCs: RFC1518 and RFC1519 which define all this.
– pjz
May 22 '09 at 2:42
16
16
RFC 1519 is obsolete for a long time. The current version is RFC 4632.
– bortzmeyer
May 22 '09 at 6:11
RFC 1519 is obsolete for a long time. The current version is RFC 4632.
– bortzmeyer
May 22 '09 at 6:11
Just got assigned a dot zero by an Amazon EC2 instance. They are sure maximising the IP's they have.
– Matt
Jun 5 '17 at 20:38
Just got assigned a dot zero by an Amazon EC2 instance. They are sure maximising the IP's they have.
– Matt
Jun 5 '17 at 20:38
@bortzmeyer, RFC 4632 is simply a BEST CURRENT PRACTICE, while RFC 1519 is a standards track RFC.
– Ron Maupin
May 27 at 3:39
@bortzmeyer, RFC 4632 is simply a BEST CURRENT PRACTICE, while RFC 1519 is a standards track RFC.
– Ron Maupin
May 27 at 3:39
add a comment |
answer to your question depends on the netmask. in general statement 'IP addresses ending in .0 or .255 is invalid' is false. take 10.0.1.0/23 - it's valid ip address.
also 10.6.43.0/255.255.252.0 aka 10.6.43.0/22 is valid.
that was the theory. most reasonable network devices [ including linux servers, windows boxes, cisco / hp / etc ] will work fine with such address, but i've seen dlink and other low-end network appliance [ routers, access points ] not accepting such addresses.
answered May 21 '09 at 20:45
pQdpQd
25.8k35597
add a comment |
answer to your question depends on the netmask. in general statement 'IP addresses ending in .0 or .255 is invalid' is false. take 10.0.1.0/23 - it's valid ip address.
also 10.6.43.0/255.255.252.0 aka 10.6.43.0/22 is valid.
that was the theory. most reasonable network devices [ including linux servers, windows boxes, cisco / hp / etc ] will work fine with such address, but i've seen dlink and other low-end network appliance [ routers, access points ] not accepting such addresses.
answered May 21 '09 at 20:45
pQdpQd
25.8k35597
add a comment |
answer to your question depends on the netmask. in general statement 'IP addresses ending in .0 or .255 is invalid' is false. take 10.0.1.0/23 - it's valid ip address.
also 10.6.43.0/255.255.252.0 aka 10.6.43.0/22 is valid.
that was the theory. most reasonable network devices [ including linux servers, windows boxes, cisco / hp / etc ] will work fine with such address, but i've seen dlink and other low-end network appliance [ routers, access points ] not accepting such addresses.
answered May 21 '09 at 20:45
pQdpQd
25.8k35597
answer to your question depends on the netmask. in general statement 'IP addresses ending in .0 or .255 is invalid' is false. take 10.0.1.0/23 - it's valid ip address.
also 10.6.43.0/255.255.252.0 aka 10.6.43.0/22 is valid.
that was the theory. most reasonable network devices [ including linux servers, windows boxes, cisco / hp / etc ] will work fine with such address, but i've seen dlink and other low-end network appliance [ routers, access points ] not accepting such addresses.
answered May 21 '09 at 20:45
pQdpQd
25.8k35597
edited May 22 '09 at 9:35
answered May 21 '09 at 20:45
pQdpQd
25.8k35597
answered May 21 '09 at 20:45
pQdpQd
25.8k35597
answered May 21 '09 at 20:45
pQdpQd
25.8k35597
25.8k35597
add a comment |
add a comment |
I found this, which claims that it is valid, depending on your subnet mask.
http://en.wikipedia.org/wiki/IPv4#Addresses_ending_in_0_or_255
answered May 21 '09 at 21:24
Alan HAlan H
1,48931616
add a comment |
I found this, which claims that it is valid, depending on your subnet mask.
http://en.wikipedia.org/wiki/IPv4#Addresses_ending_in_0_or_255
answered May 21 '09 at 21:24
Alan HAlan H
1,48931616
add a comment |
I found this, which claims that it is valid, depending on your subnet mask.
http://en.wikipedia.org/wiki/IPv4#Addresses_ending_in_0_or_255
answered May 21 '09 at 21:24
Alan HAlan H
1,48931616
I found this, which claims that it is valid, depending on your subnet mask.
http://en.wikipedia.org/wiki/IPv4#Addresses_ending_in_0_or_255
answered May 21 '09 at 21:24
Alan HAlan H
1,48931616
answered May 21 '09 at 21:24
Alan HAlan H
1,48931616
answered May 21 '09 at 21:24
Alan HAlan H
1,48931616
answered May 21 '09 at 21:24
Alan HAlan H
1,48931616
1,48931616
add a comment |
add a comment |
I'd like to add a bit about 0 for the other octets:
This one is easy: it's no problem at all, as the fairly common private network address 192.168.0.1 shows.
Of course an even more obvious example would be 127.0.0.1.
edited Aug 22 '09 at 9:39
splattne
25.8k1892144
answered Jul 4 '09 at 15:44
Joachim SauerJoachim Sauer
741316
1
-1 for obvious...
– Jon Rhoades
Aug 22 '09 at 11:36
5
+1 for pointing out the obvious
– just somebody
Oct 1 '12 at 9:47
The question isn't asking about zeroes in the other octets.
– slang
Aug 31 '17 at 16:27
2
@slang: Except it literally asks about exactly that in the last sentence.
– Joachim Sauer
Aug 31 '17 at 16:28
add a comment |
I'd like to add a bit about 0 for the other octets:
This one is easy: it's no problem at all, as the fairly common private network address 192.168.0.1 shows.
Of course an even more obvious example would be 127.0.0.1.
edited Aug 22 '09 at 9:39
splattne
25.8k1892144
answered Jul 4 '09 at 15:44
Joachim SauerJoachim Sauer
741316
1
-1 for obvious...
– Jon Rhoades
Aug 22 '09 at 11:36
5
+1 for pointing out the obvious
– just somebody
Oct 1 '12 at 9:47
The question isn't asking about zeroes in the other octets.
– slang
Aug 31 '17 at 16:27
2
@slang: Except it literally asks about exactly that in the last sentence.
– Joachim Sauer
Aug 31 '17 at 16:28
add a comment |
I'd like to add a bit about 0 for the other octets:
This one is easy: it's no problem at all, as the fairly common private network address 192.168.0.1 shows.
Of course an even more obvious example would be 127.0.0.1.
edited Aug 22 '09 at 9:39
splattne
25.8k1892144
answered Jul 4 '09 at 15:44
Joachim SauerJoachim Sauer
741316
I'd like to add a bit about 0 for the other octets:
This one is easy: it's no problem at all, as the fairly common private network address 192.168.0.1 shows.
Of course an even more obvious example would be 127.0.0.1.
edited Aug 22 '09 at 9:39
splattne
25.8k1892144
answered Jul 4 '09 at 15:44
Joachim SauerJoachim Sauer
741316
edited Aug 22 '09 at 9:39
splattne
25.8k1892144
edited Aug 22 '09 at 9:39
splattne
25.8k1892144
edited Aug 22 '09 at 9:39
splattne
25.8k1892144
25.8k1892144
answered Jul 4 '09 at 15:44
Joachim SauerJoachim Sauer
741316
answered Jul 4 '09 at 15:44
Joachim SauerJoachim Sauer
741316
answered Jul 4 '09 at 15:44
Joachim SauerJoachim Sauer
741316
741316
1
-1 for obvious...
– Jon Rhoades
Aug 22 '09 at 11:36
5
+1 for pointing out the obvious
– just somebody
Oct 1 '12 at 9:47
The question isn't asking about zeroes in the other octets.
– slang
Aug 31 '17 at 16:27
2
@slang: Except it literally asks about exactly that in the last sentence.
– Joachim Sauer
Aug 31 '17 at 16:28
add a comment |
1
-1 for obvious...
– Jon Rhoades
Aug 22 '09 at 11:36
5
+1 for pointing out the obvious
– just somebody
Oct 1 '12 at 9:47
The question isn't asking about zeroes in the other octets.
– slang
Aug 31 '17 at 16:27
2
@slang: Except it literally asks about exactly that in the last sentence.
– Joachim Sauer
Aug 31 '17 at 16:28
1
1
-1 for obvious...
– Jon Rhoades
Aug 22 '09 at 11:36
-1 for obvious...
– Jon Rhoades
Aug 22 '09 at 11:36
5
5
+1 for pointing out the obvious
– just somebody
Oct 1 '12 at 9:47
+1 for pointing out the obvious
– just somebody
Oct 1 '12 at 9:47
The question isn't asking about zeroes in the other octets.
– slang
Aug 31 '17 at 16:27
The question isn't asking about zeroes in the other octets.
– slang
Aug 31 '17 at 16:27
2
2
@slang: Except it literally asks about exactly that in the last sentence.
– Joachim Sauer
Aug 31 '17 at 16:28
@slang: Except it literally asks about exactly that in the last sentence.
– Joachim Sauer
Aug 31 '17 at 16:28
add a comment |
I have run into problems with remote networks denying IP addresses from my network if they ended with 0 (or 255) and they were from the class C range, since anything ending with 0 would be an invalid class C network.
This was a few years ago; I don't know if anyone still blocks addresses like that or not.
answered Jun 27 '09 at 12:26
Josh KelleyJosh Kelley
5331416
That just sounds like your firewall/software is a bit daft ;)
– nixgeek
Jul 4 '09 at 15:51
Every IP address on my network except .0 or .255 could access every site, IP addresses ending in .0 and .255 could access 95% of sites, but there were two or three completely different sites that they couldn't access. If it was my firewall/software, I sure couldn't figure out how.
– Josh Kelley
Jul 4 '09 at 17:22
1
These must be using firewalls configured by the same kind of people who block all ICMP and end up breaking PMTUD, or block all "invalid" TCP flags and end up breaking ECN.
– CesarB
Jul 5 '09 at 0:11
Microsoft servers allegedly do it even today. No Windows Update for you. But Microsoft has been known to break the rules since forever.
– Zdenek
Feb 20 '16 at 12:15
add a comment |
I have run into problems with remote networks denying IP addresses from my network if they ended with 0 (or 255) and they were from the class C range, since anything ending with 0 would be an invalid class C network.
This was a few years ago; I don't know if anyone still blocks addresses like that or not.
answered Jun 27 '09 at 12:26
Josh KelleyJosh Kelley
5331416
That just sounds like your firewall/software is a bit daft ;)
– nixgeek
Jul 4 '09 at 15:51
Every IP address on my network except .0 or .255 could access every site, IP addresses ending in .0 and .255 could access 95% of sites, but there were two or three completely different sites that they couldn't access. If it was my firewall/software, I sure couldn't figure out how.
– Josh Kelley
Jul 4 '09 at 17:22
1
These must be using firewalls configured by the same kind of people who block all ICMP and end up breaking PMTUD, or block all "invalid" TCP flags and end up breaking ECN.
– CesarB
Jul 5 '09 at 0:11
Microsoft servers allegedly do it even today. No Windows Update for you. But Microsoft has been known to break the rules since forever.
– Zdenek
Feb 20 '16 at 12:15
add a comment |
I have run into problems with remote networks denying IP addresses from my network if they ended with 0 (or 255) and they were from the class C range, since anything ending with 0 would be an invalid class C network.
This was a few years ago; I don't know if anyone still blocks addresses like that or not.
answered Jun 27 '09 at 12:26
Josh KelleyJosh Kelley
5331416
I have run into problems with remote networks denying IP addresses from my network if they ended with 0 (or 255) and they were from the class C range, since anything ending with 0 would be an invalid class C network.
This was a few years ago; I don't know if anyone still blocks addresses like that or not.
answered Jun 27 '09 at 12:26
Josh KelleyJosh Kelley
5331416
answered Jun 27 '09 at 12:26
Josh KelleyJosh Kelley
5331416
answered Jun 27 '09 at 12:26
Josh KelleyJosh Kelley
5331416
answered Jun 27 '09 at 12:26
Josh KelleyJosh Kelley
5331416
5331416
That just sounds like your firewall/software is a bit daft ;)
– nixgeek
Jul 4 '09 at 15:51
Every IP address on my network except .0 or .255 could access every site, IP addresses ending in .0 and .255 could access 95% of sites, but there were two or three completely different sites that they couldn't access. If it was my firewall/software, I sure couldn't figure out how.
– Josh Kelley
Jul 4 '09 at 17:22
1
These must be using firewalls configured by the same kind of people who block all ICMP and end up breaking PMTUD, or block all "invalid" TCP flags and end up breaking ECN.
– CesarB
Jul 5 '09 at 0:11
Microsoft servers allegedly do it even today. No Windows Update for you. But Microsoft has been known to break the rules since forever.
– Zdenek
Feb 20 '16 at 12:15
add a comment |
That just sounds like your firewall/software is a bit daft ;)
– nixgeek
Jul 4 '09 at 15:51
Every IP address on my network except .0 or .255 could access every site, IP addresses ending in .0 and .255 could access 95% of sites, but there were two or three completely different sites that they couldn't access. If it was my firewall/software, I sure couldn't figure out how.
– Josh Kelley
Jul 4 '09 at 17:22
1
These must be using firewalls configured by the same kind of people who block all ICMP and end up breaking PMTUD, or block all "invalid" TCP flags and end up breaking ECN.
– CesarB
Jul 5 '09 at 0:11
Microsoft servers allegedly do it even today. No Windows Update for you. But Microsoft has been known to break the rules since forever.
– Zdenek
Feb 20 '16 at 12:15
That just sounds like your firewall/software is a bit daft ;)
– nixgeek
Jul 4 '09 at 15:51
That just sounds like your firewall/software is a bit daft ;)
– nixgeek
Jul 4 '09 at 15:51
Every IP address on my network except .0 or .255 could access every site, IP addresses ending in .0 and .255 could access 95% of sites, but there were two or three completely different sites that they couldn't access. If it was my firewall/software, I sure couldn't figure out how.
– Josh Kelley
Jul 4 '09 at 17:22
Every IP address on my network except .0 or .255 could access every site, IP addresses ending in .0 and .255 could access 95% of sites, but there were two or three completely different sites that they couldn't access. If it was my firewall/software, I sure couldn't figure out how.
– Josh Kelley
Jul 4 '09 at 17:22
1
1
These must be using firewalls configured by the same kind of people who block all ICMP and end up breaking PMTUD, or block all "invalid" TCP flags and end up breaking ECN.
– CesarB
Jul 5 '09 at 0:11
These must be using firewalls configured by the same kind of people who block all ICMP and end up breaking PMTUD, or block all "invalid" TCP flags and end up breaking ECN.
– CesarB
Jul 5 '09 at 0:11
Microsoft servers allegedly do it even today. No Windows Update for you. But Microsoft has been known to break the rules since forever.
– Zdenek
Feb 20 '16 at 12:15
Microsoft servers allegedly do it even today. No Windows Update for you. But Microsoft has been known to break the rules since forever.
– Zdenek
Feb 20 '16 at 12:15
add a comment |
Just something I found that's probably noteworthy:
If you're running R-fx networks' APF script for iptables, it drops all traffic to 0.0.0.255
We had a BT customer with an address ending in .255 with a prefix of /21 .. Technically a valid IP address, however the guys at R-fx networks think there is cause for dropping packets for these addresses.
answered Jan 17 '11 at 14:10
SqueebSqueeb
122111
they are choosing to drop packets to 0.0.0.255 most likely for security purposes. 1) DOS attacks can happen by leveraging the power of a broadcast packet and 2) to completely privatize the network so no hosts can broadcast. see en.wikipedia.org/wiki/Broadcast_traffic#Security
– zamnuts
Jul 3 '13 at 23:41
add a comment |
Just something I found that's probably noteworthy:
If you're running R-fx networks' APF script for iptables, it drops all traffic to 0.0.0.255
We had a BT customer with an address ending in .255 with a prefix of /21 .. Technically a valid IP address, however the guys at R-fx networks think there is cause for dropping packets for these addresses.
answered Jan 17 '11 at 14:10
SqueebSqueeb
122111
they are choosing to drop packets to 0.0.0.255 most likely for security purposes. 1) DOS attacks can happen by leveraging the power of a broadcast packet and 2) to completely privatize the network so no hosts can broadcast. see en.wikipedia.org/wiki/Broadcast_traffic#Security
– zamnuts
Jul 3 '13 at 23:41
add a comment |
Just something I found that's probably noteworthy:
If you're running R-fx networks' APF script for iptables, it drops all traffic to 0.0.0.255
We had a BT customer with an address ending in .255 with a prefix of /21 .. Technically a valid IP address, however the guys at R-fx networks think there is cause for dropping packets for these addresses.
answered Jan 17 '11 at 14:10
SqueebSqueeb
122111
Just something I found that's probably noteworthy:
If you're running R-fx networks' APF script for iptables, it drops all traffic to 0.0.0.255
We had a BT customer with an address ending in .255 with a prefix of /21 .. Technically a valid IP address, however the guys at R-fx networks think there is cause for dropping packets for these addresses.
answered Jan 17 '11 at 14:10
SqueebSqueeb
122111
answered Jan 17 '11 at 14:10
SqueebSqueeb
122111
answered Jan 17 '11 at 14:10
SqueebSqueeb
122111
answered Jan 17 '11 at 14:10
SqueebSqueeb
122111
122111
they are choosing to drop packets to 0.0.0.255 most likely for security purposes. 1) DOS attacks can happen by leveraging the power of a broadcast packet and 2) to completely privatize the network so no hosts can broadcast. see en.wikipedia.org/wiki/Broadcast_traffic#Security
– zamnuts
Jul 3 '13 at 23:41
add a comment |
they are choosing to drop packets to 0.0.0.255 most likely for security purposes. 1) DOS attacks can happen by leveraging the power of a broadcast packet and 2) to completely privatize the network so no hosts can broadcast. see en.wikipedia.org/wiki/Broadcast_traffic#Security
– zamnuts
Jul 3 '13 at 23:41
they are choosing to drop packets to 0.0.0.255 most likely for security purposes. 1) DOS attacks can happen by leveraging the power of a broadcast packet and 2) to completely privatize the network so no hosts can broadcast. see en.wikipedia.org/wiki/Broadcast_traffic#Security
– zamnuts
Jul 3 '13 at 23:41
they are choosing to drop packets to 0.0.0.255 most likely for security purposes. 1) DOS attacks can happen by leveraging the power of a broadcast packet and 2) to completely privatize the network so no hosts can broadcast. see en.wikipedia.org/wiki/Broadcast_traffic#Security
– zamnuts
Jul 3 '13 at 23:41
add a comment |
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12
others have answered, but we run /23s in our DHCP ranges, meaning that the middle .255 and .0 addresses of the two /24s get assigned to clients. Works fine. Sometimes "knowledgeable" users freak out a little thinking they've pulled an invalid IP, but from a networking POV it works fine.
– jj33
May 21 '09 at 21:26
1
See Also: What is the network address X.Y.Z.0 used for?
– voretaq7
Nov 19 '12 at 23:07