Speed and call quality testMy IP addressIP subnet calculatorDNS reportWhoIs lookupRemote support

Internet and network

Speed and call quality testTest delay, jitter and speed, with a focus on phone calls.My IP addressYour public IPv4 and IPv6 addresses, provider and address range.WhoIs lookupWho owns a domain or IP address, when it expires, and its DNS.DNS reportEvery DNS record for a domain, with email setup checked.IP subnet calculatorWork out a network's range, mask and hosts, and split it into subnets.

Computers and devices

Update checkIs this computer, phone and browser up to date? With links to update.Camera and mic testCheck your webcam and microphone before a call.Test print pagePrint an A4 page to check a printer: edges, text, line art and colours.

Make and print

Clean textStrip hidden characters, smart quotes and odd spaces from pasted text.QR code makerMake a QR code for a link, contact or message. Nothing leaves your browser.Wi-Fi QR posterPrint an A4 poster that lets guests join your Wi-Fi by scanning.

Surftec support

Remote supportLet a Surftec engineer connect to your computer to help you.All workingA full-screen confirmation that everything is up and running.

Surftec

Surftec websiteServices, news and how to contact Surftec
Cloud Tools
Guest
GuestNot signed in

Surftec customers will be recognised automatically when they use these tools from their office network.

Customer sign-in is coming soon.

IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Prefix/120
Addresses256
/64 networksPart of one
Network
2c19:dd:c25:c25:dd:dd:dd:9700/120
First address
2c19:dd:c25:c25:dd:dd:dd:9700
Last address
2c19:dd:c25:c25:dd:dd:dd:97ff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:0c25:0c25:00dd:00dd:00dd:9700
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
7.9.d.d.0.0.d.d.0.0.d.d.0.0.5.2.c.0.5.2.c.0.d.d.0.0.9.1.c.2.ip6.arpa
Split into smaller subnets/128
/121 (2)/122 (4)/123 (8)/124 (16)/127 (128)/128 (256)

2c19:dd:c25:c25:dd:dd:dd:9700/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:c25:c25:dd:dd:dd:9700/1282c19:dd:c25:c25:dd:dd:dd:9700
22c19:dd:c25:c25:dd:dd:dd:9701/1282c19:dd:c25:c25:dd:dd:dd:9701
32c19:dd:c25:c25:dd:dd:dd:9702/1282c19:dd:c25:c25:dd:dd:dd:9702
42c19:dd:c25:c25:dd:dd:dd:9703/1282c19:dd:c25:c25:dd:dd:dd:9703
52c19:dd:c25:c25:dd:dd:dd:9704/1282c19:dd:c25:c25:dd:dd:dd:9704
62c19:dd:c25:c25:dd:dd:dd:9705/1282c19:dd:c25:c25:dd:dd:dd:9705
72c19:dd:c25:c25:dd:dd:dd:9706/1282c19:dd:c25:c25:dd:dd:dd:9706
82c19:dd:c25:c25:dd:dd:dd:9707/1282c19:dd:c25:c25:dd:dd:dd:9707
92c19:dd:c25:c25:dd:dd:dd:9708/1282c19:dd:c25:c25:dd:dd:dd:9708
102c19:dd:c25:c25:dd:dd:dd:9709/1282c19:dd:c25:c25:dd:dd:dd:9709
112c19:dd:c25:c25:dd:dd:dd:970a/1282c19:dd:c25:c25:dd:dd:dd:970a
122c19:dd:c25:c25:dd:dd:dd:970b/1282c19:dd:c25:c25:dd:dd:dd:970b
132c19:dd:c25:c25:dd:dd:dd:970c/1282c19:dd:c25:c25:dd:dd:dd:970c
142c19:dd:c25:c25:dd:dd:dd:970d/1282c19:dd:c25:c25:dd:dd:dd:970d
152c19:dd:c25:c25:dd:dd:dd:970e/1282c19:dd:c25:c25:dd:dd:dd:970e
162c19:dd:c25:c25:dd:dd:dd:970f/1282c19:dd:c25:c25:dd:dd:dd:970f
172c19:dd:c25:c25:dd:dd:dd:9710/1282c19:dd:c25:c25:dd:dd:dd:9710
182c19:dd:c25:c25:dd:dd:dd:9711/1282c19:dd:c25:c25:dd:dd:dd:9711
192c19:dd:c25:c25:dd:dd:dd:9712/1282c19:dd:c25:c25:dd:dd:dd:9712
202c19:dd:c25:c25:dd:dd:dd:9713/1282c19:dd:c25:c25:dd:dd:dd:9713
212c19:dd:c25:c25:dd:dd:dd:9714/1282c19:dd:c25:c25:dd:dd:dd:9714
222c19:dd:c25:c25:dd:dd:dd:9715/1282c19:dd:c25:c25:dd:dd:dd:9715
232c19:dd:c25:c25:dd:dd:dd:9716/1282c19:dd:c25:c25:dd:dd:dd:9716
242c19:dd:c25:c25:dd:dd:dd:9717/1282c19:dd:c25:c25:dd:dd:dd:9717
252c19:dd:c25:c25:dd:dd:dd:9718/1282c19:dd:c25:c25:dd:dd:dd:9718
262c19:dd:c25:c25:dd:dd:dd:9719/1282c19:dd:c25:c25:dd:dd:dd:9719
272c19:dd:c25:c25:dd:dd:dd:971a/1282c19:dd:c25:c25:dd:dd:dd:971a
282c19:dd:c25:c25:dd:dd:dd:971b/1282c19:dd:c25:c25:dd:dd:dd:971b
292c19:dd:c25:c25:dd:dd:dd:971c/1282c19:dd:c25:c25:dd:dd:dd:971c
302c19:dd:c25:c25:dd:dd:dd:971d/1282c19:dd:c25:c25:dd:dd:dd:971d
312c19:dd:c25:c25:dd:dd:dd:971e/1282c19:dd:c25:c25:dd:dd:dd:971e
322c19:dd:c25:c25:dd:dd:dd:971f/1282c19:dd:c25:c25:dd:dd:dd:971f
332c19:dd:c25:c25:dd:dd:dd:9720/1282c19:dd:c25:c25:dd:dd:dd:9720
342c19:dd:c25:c25:dd:dd:dd:9721/1282c19:dd:c25:c25:dd:dd:dd:9721
352c19:dd:c25:c25:dd:dd:dd:9722/1282c19:dd:c25:c25:dd:dd:dd:9722
362c19:dd:c25:c25:dd:dd:dd:9723/1282c19:dd:c25:c25:dd:dd:dd:9723
372c19:dd:c25:c25:dd:dd:dd:9724/1282c19:dd:c25:c25:dd:dd:dd:9724
382c19:dd:c25:c25:dd:dd:dd:9725/1282c19:dd:c25:c25:dd:dd:dd:9725
392c19:dd:c25:c25:dd:dd:dd:9726/1282c19:dd:c25:c25:dd:dd:dd:9726
402c19:dd:c25:c25:dd:dd:dd:9727/1282c19:dd:c25:c25:dd:dd:dd:9727
412c19:dd:c25:c25:dd:dd:dd:9728/1282c19:dd:c25:c25:dd:dd:dd:9728
422c19:dd:c25:c25:dd:dd:dd:9729/1282c19:dd:c25:c25:dd:dd:dd:9729
432c19:dd:c25:c25:dd:dd:dd:972a/1282c19:dd:c25:c25:dd:dd:dd:972a
442c19:dd:c25:c25:dd:dd:dd:972b/1282c19:dd:c25:c25:dd:dd:dd:972b
452c19:dd:c25:c25:dd:dd:dd:972c/1282c19:dd:c25:c25:dd:dd:dd:972c
462c19:dd:c25:c25:dd:dd:dd:972d/1282c19:dd:c25:c25:dd:dd:dd:972d
472c19:dd:c25:c25:dd:dd:dd:972e/1282c19:dd:c25:c25:dd:dd:dd:972e
482c19:dd:c25:c25:dd:dd:dd:972f/1282c19:dd:c25:c25:dd:dd:dd:972f
492c19:dd:c25:c25:dd:dd:dd:9730/1282c19:dd:c25:c25:dd:dd:dd:9730
502c19:dd:c25:c25:dd:dd:dd:9731/1282c19:dd:c25:c25:dd:dd:dd:9731
512c19:dd:c25:c25:dd:dd:dd:9732/1282c19:dd:c25:c25:dd:dd:dd:9732
522c19:dd:c25:c25:dd:dd:dd:9733/1282c19:dd:c25:c25:dd:dd:dd:9733
532c19:dd:c25:c25:dd:dd:dd:9734/1282c19:dd:c25:c25:dd:dd:dd:9734
542c19:dd:c25:c25:dd:dd:dd:9735/1282c19:dd:c25:c25:dd:dd:dd:9735
552c19:dd:c25:c25:dd:dd:dd:9736/1282c19:dd:c25:c25:dd:dd:dd:9736
562c19:dd:c25:c25:dd:dd:dd:9737/1282c19:dd:c25:c25:dd:dd:dd:9737
572c19:dd:c25:c25:dd:dd:dd:9738/1282c19:dd:c25:c25:dd:dd:dd:9738
582c19:dd:c25:c25:dd:dd:dd:9739/1282c19:dd:c25:c25:dd:dd:dd:9739
592c19:dd:c25:c25:dd:dd:dd:973a/1282c19:dd:c25:c25:dd:dd:dd:973a
602c19:dd:c25:c25:dd:dd:dd:973b/1282c19:dd:c25:c25:dd:dd:dd:973b
612c19:dd:c25:c25:dd:dd:dd:973c/1282c19:dd:c25:c25:dd:dd:dd:973c
622c19:dd:c25:c25:dd:dd:dd:973d/1282c19:dd:c25:c25:dd:dd:dd:973d
632c19:dd:c25:c25:dd:dd:dd:973e/1282c19:dd:c25:c25:dd:dd:dd:973e
642c19:dd:c25:c25:dd:dd:dd:973f/1282c19:dd:c25:c25:dd:dd:dd:973f
652c19:dd:c25:c25:dd:dd:dd:9740/1282c19:dd:c25:c25:dd:dd:dd:9740
662c19:dd:c25:c25:dd:dd:dd:9741/1282c19:dd:c25:c25:dd:dd:dd:9741
672c19:dd:c25:c25:dd:dd:dd:9742/1282c19:dd:c25:c25:dd:dd:dd:9742
682c19:dd:c25:c25:dd:dd:dd:9743/1282c19:dd:c25:c25:dd:dd:dd:9743
692c19:dd:c25:c25:dd:dd:dd:9744/1282c19:dd:c25:c25:dd:dd:dd:9744
702c19:dd:c25:c25:dd:dd:dd:9745/1282c19:dd:c25:c25:dd:dd:dd:9745
712c19:dd:c25:c25:dd:dd:dd:9746/1282c19:dd:c25:c25:dd:dd:dd:9746
722c19:dd:c25:c25:dd:dd:dd:9747/1282c19:dd:c25:c25:dd:dd:dd:9747
732c19:dd:c25:c25:dd:dd:dd:9748/1282c19:dd:c25:c25:dd:dd:dd:9748
742c19:dd:c25:c25:dd:dd:dd:9749/1282c19:dd:c25:c25:dd:dd:dd:9749
752c19:dd:c25:c25:dd:dd:dd:974a/1282c19:dd:c25:c25:dd:dd:dd:974a
762c19:dd:c25:c25:dd:dd:dd:974b/1282c19:dd:c25:c25:dd:dd:dd:974b
772c19:dd:c25:c25:dd:dd:dd:974c/1282c19:dd:c25:c25:dd:dd:dd:974c
782c19:dd:c25:c25:dd:dd:dd:974d/1282c19:dd:c25:c25:dd:dd:dd:974d
792c19:dd:c25:c25:dd:dd:dd:974e/1282c19:dd:c25:c25:dd:dd:dd:974e
802c19:dd:c25:c25:dd:dd:dd:974f/1282c19:dd:c25:c25:dd:dd:dd:974f
812c19:dd:c25:c25:dd:dd:dd:9750/1282c19:dd:c25:c25:dd:dd:dd:9750
822c19:dd:c25:c25:dd:dd:dd:9751/1282c19:dd:c25:c25:dd:dd:dd:9751
832c19:dd:c25:c25:dd:dd:dd:9752/1282c19:dd:c25:c25:dd:dd:dd:9752
842c19:dd:c25:c25:dd:dd:dd:9753/1282c19:dd:c25:c25:dd:dd:dd:9753
852c19:dd:c25:c25:dd:dd:dd:9754/1282c19:dd:c25:c25:dd:dd:dd:9754
862c19:dd:c25:c25:dd:dd:dd:9755/1282c19:dd:c25:c25:dd:dd:dd:9755
872c19:dd:c25:c25:dd:dd:dd:9756/1282c19:dd:c25:c25:dd:dd:dd:9756
882c19:dd:c25:c25:dd:dd:dd:9757/1282c19:dd:c25:c25:dd:dd:dd:9757
892c19:dd:c25:c25:dd:dd:dd:9758/1282c19:dd:c25:c25:dd:dd:dd:9758
902c19:dd:c25:c25:dd:dd:dd:9759/1282c19:dd:c25:c25:dd:dd:dd:9759
912c19:dd:c25:c25:dd:dd:dd:975a/1282c19:dd:c25:c25:dd:dd:dd:975a
922c19:dd:c25:c25:dd:dd:dd:975b/1282c19:dd:c25:c25:dd:dd:dd:975b
932c19:dd:c25:c25:dd:dd:dd:975c/1282c19:dd:c25:c25:dd:dd:dd:975c
942c19:dd:c25:c25:dd:dd:dd:975d/1282c19:dd:c25:c25:dd:dd:dd:975d
952c19:dd:c25:c25:dd:dd:dd:975e/1282c19:dd:c25:c25:dd:dd:dd:975e
962c19:dd:c25:c25:dd:dd:dd:975f/1282c19:dd:c25:c25:dd:dd:dd:975f
972c19:dd:c25:c25:dd:dd:dd:9760/1282c19:dd:c25:c25:dd:dd:dd:9760
982c19:dd:c25:c25:dd:dd:dd:9761/1282c19:dd:c25:c25:dd:dd:dd:9761
992c19:dd:c25:c25:dd:dd:dd:9762/1282c19:dd:c25:c25:dd:dd:dd:9762
1002c19:dd:c25:c25:dd:dd:dd:9763/1282c19:dd:c25:c25:dd:dd:dd:9763
1012c19:dd:c25:c25:dd:dd:dd:9764/1282c19:dd:c25:c25:dd:dd:dd:9764
1022c19:dd:c25:c25:dd:dd:dd:9765/1282c19:dd:c25:c25:dd:dd:dd:9765
1032c19:dd:c25:c25:dd:dd:dd:9766/1282c19:dd:c25:c25:dd:dd:dd:9766
1042c19:dd:c25:c25:dd:dd:dd:9767/1282c19:dd:c25:c25:dd:dd:dd:9767
1052c19:dd:c25:c25:dd:dd:dd:9768/1282c19:dd:c25:c25:dd:dd:dd:9768
1062c19:dd:c25:c25:dd:dd:dd:9769/1282c19:dd:c25:c25:dd:dd:dd:9769
1072c19:dd:c25:c25:dd:dd:dd:976a/1282c19:dd:c25:c25:dd:dd:dd:976a
1082c19:dd:c25:c25:dd:dd:dd:976b/1282c19:dd:c25:c25:dd:dd:dd:976b
1092c19:dd:c25:c25:dd:dd:dd:976c/1282c19:dd:c25:c25:dd:dd:dd:976c
1102c19:dd:c25:c25:dd:dd:dd:976d/1282c19:dd:c25:c25:dd:dd:dd:976d
1112c19:dd:c25:c25:dd:dd:dd:976e/1282c19:dd:c25:c25:dd:dd:dd:976e
1122c19:dd:c25:c25:dd:dd:dd:976f/1282c19:dd:c25:c25:dd:dd:dd:976f
1132c19:dd:c25:c25:dd:dd:dd:9770/1282c19:dd:c25:c25:dd:dd:dd:9770
1142c19:dd:c25:c25:dd:dd:dd:9771/1282c19:dd:c25:c25:dd:dd:dd:9771
1152c19:dd:c25:c25:dd:dd:dd:9772/1282c19:dd:c25:c25:dd:dd:dd:9772
1162c19:dd:c25:c25:dd:dd:dd:9773/1282c19:dd:c25:c25:dd:dd:dd:9773
1172c19:dd:c25:c25:dd:dd:dd:9774/1282c19:dd:c25:c25:dd:dd:dd:9774
1182c19:dd:c25:c25:dd:dd:dd:9775/1282c19:dd:c25:c25:dd:dd:dd:9775
1192c19:dd:c25:c25:dd:dd:dd:9776/1282c19:dd:c25:c25:dd:dd:dd:9776
1202c19:dd:c25:c25:dd:dd:dd:9777/1282c19:dd:c25:c25:dd:dd:dd:9777
1212c19:dd:c25:c25:dd:dd:dd:9778/1282c19:dd:c25:c25:dd:dd:dd:9778
1222c19:dd:c25:c25:dd:dd:dd:9779/1282c19:dd:c25:c25:dd:dd:dd:9779
1232c19:dd:c25:c25:dd:dd:dd:977a/1282c19:dd:c25:c25:dd:dd:dd:977a
1242c19:dd:c25:c25:dd:dd:dd:977b/1282c19:dd:c25:c25:dd:dd:dd:977b
1252c19:dd:c25:c25:dd:dd:dd:977c/1282c19:dd:c25:c25:dd:dd:dd:977c
1262c19:dd:c25:c25:dd:dd:dd:977d/1282c19:dd:c25:c25:dd:dd:dd:977d
1272c19:dd:c25:c25:dd:dd:dd:977e/1282c19:dd:c25:c25:dd:dd:dd:977e
1282c19:dd:c25:c25:dd:dd:dd:977f/1282c19:dd:c25:c25:dd:dd:dd:977f
1292c19:dd:c25:c25:dd:dd:dd:9780/1282c19:dd:c25:c25:dd:dd:dd:9780
1302c19:dd:c25:c25:dd:dd:dd:9781/1282c19:dd:c25:c25:dd:dd:dd:9781
1312c19:dd:c25:c25:dd:dd:dd:9782/1282c19:dd:c25:c25:dd:dd:dd:9782
1322c19:dd:c25:c25:dd:dd:dd:9783/1282c19:dd:c25:c25:dd:dd:dd:9783
1332c19:dd:c25:c25:dd:dd:dd:9784/1282c19:dd:c25:c25:dd:dd:dd:9784
1342c19:dd:c25:c25:dd:dd:dd:9785/1282c19:dd:c25:c25:dd:dd:dd:9785
1352c19:dd:c25:c25:dd:dd:dd:9786/1282c19:dd:c25:c25:dd:dd:dd:9786
1362c19:dd:c25:c25:dd:dd:dd:9787/1282c19:dd:c25:c25:dd:dd:dd:9787
1372c19:dd:c25:c25:dd:dd:dd:9788/1282c19:dd:c25:c25:dd:dd:dd:9788
1382c19:dd:c25:c25:dd:dd:dd:9789/1282c19:dd:c25:c25:dd:dd:dd:9789
1392c19:dd:c25:c25:dd:dd:dd:978a/1282c19:dd:c25:c25:dd:dd:dd:978a
1402c19:dd:c25:c25:dd:dd:dd:978b/1282c19:dd:c25:c25:dd:dd:dd:978b
1412c19:dd:c25:c25:dd:dd:dd:978c/1282c19:dd:c25:c25:dd:dd:dd:978c
1422c19:dd:c25:c25:dd:dd:dd:978d/1282c19:dd:c25:c25:dd:dd:dd:978d
1432c19:dd:c25:c25:dd:dd:dd:978e/1282c19:dd:c25:c25:dd:dd:dd:978e
1442c19:dd:c25:c25:dd:dd:dd:978f/1282c19:dd:c25:c25:dd:dd:dd:978f
1452c19:dd:c25:c25:dd:dd:dd:9790/1282c19:dd:c25:c25:dd:dd:dd:9790
1462c19:dd:c25:c25:dd:dd:dd:9791/1282c19:dd:c25:c25:dd:dd:dd:9791
1472c19:dd:c25:c25:dd:dd:dd:9792/1282c19:dd:c25:c25:dd:dd:dd:9792
1482c19:dd:c25:c25:dd:dd:dd:9793/1282c19:dd:c25:c25:dd:dd:dd:9793
1492c19:dd:c25:c25:dd:dd:dd:9794/1282c19:dd:c25:c25:dd:dd:dd:9794
1502c19:dd:c25:c25:dd:dd:dd:9795/1282c19:dd:c25:c25:dd:dd:dd:9795
1512c19:dd:c25:c25:dd:dd:dd:9796/1282c19:dd:c25:c25:dd:dd:dd:9796
1522c19:dd:c25:c25:dd:dd:dd:9797/1282c19:dd:c25:c25:dd:dd:dd:9797
1532c19:dd:c25:c25:dd:dd:dd:9798/1282c19:dd:c25:c25:dd:dd:dd:9798
1542c19:dd:c25:c25:dd:dd:dd:9799/1282c19:dd:c25:c25:dd:dd:dd:9799
1552c19:dd:c25:c25:dd:dd:dd:979a/1282c19:dd:c25:c25:dd:dd:dd:979a
1562c19:dd:c25:c25:dd:dd:dd:979b/1282c19:dd:c25:c25:dd:dd:dd:979b
1572c19:dd:c25:c25:dd:dd:dd:979c/1282c19:dd:c25:c25:dd:dd:dd:979c
1582c19:dd:c25:c25:dd:dd:dd:979d/1282c19:dd:c25:c25:dd:dd:dd:979d
1592c19:dd:c25:c25:dd:dd:dd:979e/1282c19:dd:c25:c25:dd:dd:dd:979e
1602c19:dd:c25:c25:dd:dd:dd:979f/1282c19:dd:c25:c25:dd:dd:dd:979f
1612c19:dd:c25:c25:dd:dd:dd:97a0/1282c19:dd:c25:c25:dd:dd:dd:97a0
1622c19:dd:c25:c25:dd:dd:dd:97a1/1282c19:dd:c25:c25:dd:dd:dd:97a1
1632c19:dd:c25:c25:dd:dd:dd:97a2/1282c19:dd:c25:c25:dd:dd:dd:97a2
1642c19:dd:c25:c25:dd:dd:dd:97a3/1282c19:dd:c25:c25:dd:dd:dd:97a3
1652c19:dd:c25:c25:dd:dd:dd:97a4/1282c19:dd:c25:c25:dd:dd:dd:97a4
1662c19:dd:c25:c25:dd:dd:dd:97a5/1282c19:dd:c25:c25:dd:dd:dd:97a5
1672c19:dd:c25:c25:dd:dd:dd:97a6/1282c19:dd:c25:c25:dd:dd:dd:97a6
1682c19:dd:c25:c25:dd:dd:dd:97a7/1282c19:dd:c25:c25:dd:dd:dd:97a7
1692c19:dd:c25:c25:dd:dd:dd:97a8/1282c19:dd:c25:c25:dd:dd:dd:97a8
1702c19:dd:c25:c25:dd:dd:dd:97a9/1282c19:dd:c25:c25:dd:dd:dd:97a9
1712c19:dd:c25:c25:dd:dd:dd:97aa/1282c19:dd:c25:c25:dd:dd:dd:97aa
1722c19:dd:c25:c25:dd:dd:dd:97ab/1282c19:dd:c25:c25:dd:dd:dd:97ab
1732c19:dd:c25:c25:dd:dd:dd:97ac/1282c19:dd:c25:c25:dd:dd:dd:97ac
1742c19:dd:c25:c25:dd:dd:dd:97ad/1282c19:dd:c25:c25:dd:dd:dd:97ad
1752c19:dd:c25:c25:dd:dd:dd:97ae/1282c19:dd:c25:c25:dd:dd:dd:97ae
1762c19:dd:c25:c25:dd:dd:dd:97af/1282c19:dd:c25:c25:dd:dd:dd:97af
1772c19:dd:c25:c25:dd:dd:dd:97b0/1282c19:dd:c25:c25:dd:dd:dd:97b0
1782c19:dd:c25:c25:dd:dd:dd:97b1/1282c19:dd:c25:c25:dd:dd:dd:97b1
1792c19:dd:c25:c25:dd:dd:dd:97b2/1282c19:dd:c25:c25:dd:dd:dd:97b2
1802c19:dd:c25:c25:dd:dd:dd:97b3/1282c19:dd:c25:c25:dd:dd:dd:97b3
1812c19:dd:c25:c25:dd:dd:dd:97b4/1282c19:dd:c25:c25:dd:dd:dd:97b4
1822c19:dd:c25:c25:dd:dd:dd:97b5/1282c19:dd:c25:c25:dd:dd:dd:97b5
1832c19:dd:c25:c25:dd:dd:dd:97b6/1282c19:dd:c25:c25:dd:dd:dd:97b6
1842c19:dd:c25:c25:dd:dd:dd:97b7/1282c19:dd:c25:c25:dd:dd:dd:97b7
1852c19:dd:c25:c25:dd:dd:dd:97b8/1282c19:dd:c25:c25:dd:dd:dd:97b8
1862c19:dd:c25:c25:dd:dd:dd:97b9/1282c19:dd:c25:c25:dd:dd:dd:97b9
1872c19:dd:c25:c25:dd:dd:dd:97ba/1282c19:dd:c25:c25:dd:dd:dd:97ba
1882c19:dd:c25:c25:dd:dd:dd:97bb/1282c19:dd:c25:c25:dd:dd:dd:97bb
1892c19:dd:c25:c25:dd:dd:dd:97bc/1282c19:dd:c25:c25:dd:dd:dd:97bc
1902c19:dd:c25:c25:dd:dd:dd:97bd/1282c19:dd:c25:c25:dd:dd:dd:97bd
1912c19:dd:c25:c25:dd:dd:dd:97be/1282c19:dd:c25:c25:dd:dd:dd:97be
1922c19:dd:c25:c25:dd:dd:dd:97bf/1282c19:dd:c25:c25:dd:dd:dd:97bf
1932c19:dd:c25:c25:dd:dd:dd:97c0/1282c19:dd:c25:c25:dd:dd:dd:97c0
1942c19:dd:c25:c25:dd:dd:dd:97c1/1282c19:dd:c25:c25:dd:dd:dd:97c1
1952c19:dd:c25:c25:dd:dd:dd:97c2/1282c19:dd:c25:c25:dd:dd:dd:97c2
1962c19:dd:c25:c25:dd:dd:dd:97c3/1282c19:dd:c25:c25:dd:dd:dd:97c3
1972c19:dd:c25:c25:dd:dd:dd:97c4/1282c19:dd:c25:c25:dd:dd:dd:97c4
1982c19:dd:c25:c25:dd:dd:dd:97c5/1282c19:dd:c25:c25:dd:dd:dd:97c5
1992c19:dd:c25:c25:dd:dd:dd:97c6/1282c19:dd:c25:c25:dd:dd:dd:97c6
2002c19:dd:c25:c25:dd:dd:dd:97c7/1282c19:dd:c25:c25:dd:dd:dd:97c7
2012c19:dd:c25:c25:dd:dd:dd:97c8/1282c19:dd:c25:c25:dd:dd:dd:97c8
2022c19:dd:c25:c25:dd:dd:dd:97c9/1282c19:dd:c25:c25:dd:dd:dd:97c9
2032c19:dd:c25:c25:dd:dd:dd:97ca/1282c19:dd:c25:c25:dd:dd:dd:97ca
2042c19:dd:c25:c25:dd:dd:dd:97cb/1282c19:dd:c25:c25:dd:dd:dd:97cb
2052c19:dd:c25:c25:dd:dd:dd:97cc/1282c19:dd:c25:c25:dd:dd:dd:97cc
2062c19:dd:c25:c25:dd:dd:dd:97cd/1282c19:dd:c25:c25:dd:dd:dd:97cd
2072c19:dd:c25:c25:dd:dd:dd:97ce/1282c19:dd:c25:c25:dd:dd:dd:97ce
2082c19:dd:c25:c25:dd:dd:dd:97cf/1282c19:dd:c25:c25:dd:dd:dd:97cf
2092c19:dd:c25:c25:dd:dd:dd:97d0/1282c19:dd:c25:c25:dd:dd:dd:97d0
2102c19:dd:c25:c25:dd:dd:dd:97d1/1282c19:dd:c25:c25:dd:dd:dd:97d1
2112c19:dd:c25:c25:dd:dd:dd:97d2/1282c19:dd:c25:c25:dd:dd:dd:97d2
2122c19:dd:c25:c25:dd:dd:dd:97d3/1282c19:dd:c25:c25:dd:dd:dd:97d3
2132c19:dd:c25:c25:dd:dd:dd:97d4/1282c19:dd:c25:c25:dd:dd:dd:97d4
2142c19:dd:c25:c25:dd:dd:dd:97d5/1282c19:dd:c25:c25:dd:dd:dd:97d5
2152c19:dd:c25:c25:dd:dd:dd:97d6/1282c19:dd:c25:c25:dd:dd:dd:97d6
2162c19:dd:c25:c25:dd:dd:dd:97d7/1282c19:dd:c25:c25:dd:dd:dd:97d7
2172c19:dd:c25:c25:dd:dd:dd:97d8/1282c19:dd:c25:c25:dd:dd:dd:97d8
2182c19:dd:c25:c25:dd:dd:dd:97d9/1282c19:dd:c25:c25:dd:dd:dd:97d9
2192c19:dd:c25:c25:dd:dd:dd:97da/1282c19:dd:c25:c25:dd:dd:dd:97da
2202c19:dd:c25:c25:dd:dd:dd:97db/1282c19:dd:c25:c25:dd:dd:dd:97db
2212c19:dd:c25:c25:dd:dd:dd:97dc/1282c19:dd:c25:c25:dd:dd:dd:97dc
2222c19:dd:c25:c25:dd:dd:dd:97dd/1282c19:dd:c25:c25:dd:dd:dd:97dd
2232c19:dd:c25:c25:dd:dd:dd:97de/1282c19:dd:c25:c25:dd:dd:dd:97de
2242c19:dd:c25:c25:dd:dd:dd:97df/1282c19:dd:c25:c25:dd:dd:dd:97df
2252c19:dd:c25:c25:dd:dd:dd:97e0/1282c19:dd:c25:c25:dd:dd:dd:97e0
2262c19:dd:c25:c25:dd:dd:dd:97e1/1282c19:dd:c25:c25:dd:dd:dd:97e1
2272c19:dd:c25:c25:dd:dd:dd:97e2/1282c19:dd:c25:c25:dd:dd:dd:97e2
2282c19:dd:c25:c25:dd:dd:dd:97e3/1282c19:dd:c25:c25:dd:dd:dd:97e3
2292c19:dd:c25:c25:dd:dd:dd:97e4/1282c19:dd:c25:c25:dd:dd:dd:97e4
2302c19:dd:c25:c25:dd:dd:dd:97e5/1282c19:dd:c25:c25:dd:dd:dd:97e5
2312c19:dd:c25:c25:dd:dd:dd:97e6/1282c19:dd:c25:c25:dd:dd:dd:97e6
2322c19:dd:c25:c25:dd:dd:dd:97e7/1282c19:dd:c25:c25:dd:dd:dd:97e7
2332c19:dd:c25:c25:dd:dd:dd:97e8/1282c19:dd:c25:c25:dd:dd:dd:97e8
2342c19:dd:c25:c25:dd:dd:dd:97e9/1282c19:dd:c25:c25:dd:dd:dd:97e9
2352c19:dd:c25:c25:dd:dd:dd:97ea/1282c19:dd:c25:c25:dd:dd:dd:97ea
2362c19:dd:c25:c25:dd:dd:dd:97eb/1282c19:dd:c25:c25:dd:dd:dd:97eb
2372c19:dd:c25:c25:dd:dd:dd:97ec/1282c19:dd:c25:c25:dd:dd:dd:97ec
2382c19:dd:c25:c25:dd:dd:dd:97ed/1282c19:dd:c25:c25:dd:dd:dd:97ed
2392c19:dd:c25:c25:dd:dd:dd:97ee/1282c19:dd:c25:c25:dd:dd:dd:97ee
2402c19:dd:c25:c25:dd:dd:dd:97ef/1282c19:dd:c25:c25:dd:dd:dd:97ef
2412c19:dd:c25:c25:dd:dd:dd:97f0/1282c19:dd:c25:c25:dd:dd:dd:97f0
2422c19:dd:c25:c25:dd:dd:dd:97f1/1282c19:dd:c25:c25:dd:dd:dd:97f1
2432c19:dd:c25:c25:dd:dd:dd:97f2/1282c19:dd:c25:c25:dd:dd:dd:97f2
2442c19:dd:c25:c25:dd:dd:dd:97f3/1282c19:dd:c25:c25:dd:dd:dd:97f3
2452c19:dd:c25:c25:dd:dd:dd:97f4/1282c19:dd:c25:c25:dd:dd:dd:97f4
2462c19:dd:c25:c25:dd:dd:dd:97f5/1282c19:dd:c25:c25:dd:dd:dd:97f5
2472c19:dd:c25:c25:dd:dd:dd:97f6/1282c19:dd:c25:c25:dd:dd:dd:97f6
2482c19:dd:c25:c25:dd:dd:dd:97f7/1282c19:dd:c25:c25:dd:dd:dd:97f7
2492c19:dd:c25:c25:dd:dd:dd:97f8/1282c19:dd:c25:c25:dd:dd:dd:97f8
2502c19:dd:c25:c25:dd:dd:dd:97f9/1282c19:dd:c25:c25:dd:dd:dd:97f9
2512c19:dd:c25:c25:dd:dd:dd:97fa/1282c19:dd:c25:c25:dd:dd:dd:97fa
2522c19:dd:c25:c25:dd:dd:dd:97fb/1282c19:dd:c25:c25:dd:dd:dd:97fb
2532c19:dd:c25:c25:dd:dd:dd:97fc/1282c19:dd:c25:c25:dd:dd:dd:97fc
2542c19:dd:c25:c25:dd:dd:dd:97fd/1282c19:dd:c25:c25:dd:dd:dd:97fd
2552c19:dd:c25:c25:dd:dd:dd:97fe/1282c19:dd:c25:c25:dd:dd:dd:97fe
2562c19:dd:c25:c25:dd:dd:dd:97ff/1282c19:dd:c25:c25:dd:dd:dd:97ff

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.