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/116
Addresses4,096
/64 networksPart of one
Network
2c19:dd:d9:dd:c25:dd0:dd08:3000/116
First address
2c19:dd:d9:dd:c25:dd0:dd08:3000
Last address
2c19:dd:d9:dd:c25:dd0:dd08:3fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0dd0:dd08:3000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
3.8.0.d.d.0.d.d.0.5.2.c.0.d.d.0.0.9.d.0.0.d.d.0.0.9.1.c.2.ip6.arpa
Split into smaller subnets/127
/117 (2)/118 (4)/119 (8)/120 (16)/124 (256)/127 (2,048)/128 (4,096)

2c19:dd:d9:dd:c25:dd0:dd08:3000/116 makes 2,048 subnets of /127; the first 256 are listed.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:dd0:dd08:3000/1272c19:dd:d9:dd:c25:dd0:dd08:3001
22c19:dd:d9:dd:c25:dd0:dd08:3002/1272c19:dd:d9:dd:c25:dd0:dd08:3003
32c19:dd:d9:dd:c25:dd0:dd08:3004/1272c19:dd:d9:dd:c25:dd0:dd08:3005
42c19:dd:d9:dd:c25:dd0:dd08:3006/1272c19:dd:d9:dd:c25:dd0:dd08:3007
52c19:dd:d9:dd:c25:dd0:dd08:3008/1272c19:dd:d9:dd:c25:dd0:dd08:3009
62c19:dd:d9:dd:c25:dd0:dd08:300a/1272c19:dd:d9:dd:c25:dd0:dd08:300b
72c19:dd:d9:dd:c25:dd0:dd08:300c/1272c19:dd:d9:dd:c25:dd0:dd08:300d
82c19:dd:d9:dd:c25:dd0:dd08:300e/1272c19:dd:d9:dd:c25:dd0:dd08:300f
92c19:dd:d9:dd:c25:dd0:dd08:3010/1272c19:dd:d9:dd:c25:dd0:dd08:3011
102c19:dd:d9:dd:c25:dd0:dd08:3012/1272c19:dd:d9:dd:c25:dd0:dd08:3013
112c19:dd:d9:dd:c25:dd0:dd08:3014/1272c19:dd:d9:dd:c25:dd0:dd08:3015
122c19:dd:d9:dd:c25:dd0:dd08:3016/1272c19:dd:d9:dd:c25:dd0:dd08:3017
132c19:dd:d9:dd:c25:dd0:dd08:3018/1272c19:dd:d9:dd:c25:dd0:dd08:3019
142c19:dd:d9:dd:c25:dd0:dd08:301a/1272c19:dd:d9:dd:c25:dd0:dd08:301b
152c19:dd:d9:dd:c25:dd0:dd08:301c/1272c19:dd:d9:dd:c25:dd0:dd08:301d
162c19:dd:d9:dd:c25:dd0:dd08:301e/1272c19:dd:d9:dd:c25:dd0:dd08:301f
172c19:dd:d9:dd:c25:dd0:dd08:3020/1272c19:dd:d9:dd:c25:dd0:dd08:3021
182c19:dd:d9:dd:c25:dd0:dd08:3022/1272c19:dd:d9:dd:c25:dd0:dd08:3023
192c19:dd:d9:dd:c25:dd0:dd08:3024/1272c19:dd:d9:dd:c25:dd0:dd08:3025
202c19:dd:d9:dd:c25:dd0:dd08:3026/1272c19:dd:d9:dd:c25:dd0:dd08:3027
212c19:dd:d9:dd:c25:dd0:dd08:3028/1272c19:dd:d9:dd:c25:dd0:dd08:3029
222c19:dd:d9:dd:c25:dd0:dd08:302a/1272c19:dd:d9:dd:c25:dd0:dd08:302b
232c19:dd:d9:dd:c25:dd0:dd08:302c/1272c19:dd:d9:dd:c25:dd0:dd08:302d
242c19:dd:d9:dd:c25:dd0:dd08:302e/1272c19:dd:d9:dd:c25:dd0:dd08:302f
252c19:dd:d9:dd:c25:dd0:dd08:3030/1272c19:dd:d9:dd:c25:dd0:dd08:3031
262c19:dd:d9:dd:c25:dd0:dd08:3032/1272c19:dd:d9:dd:c25:dd0:dd08:3033
272c19:dd:d9:dd:c25:dd0:dd08:3034/1272c19:dd:d9:dd:c25:dd0:dd08:3035
282c19:dd:d9:dd:c25:dd0:dd08:3036/1272c19:dd:d9:dd:c25:dd0:dd08:3037
292c19:dd:d9:dd:c25:dd0:dd08:3038/1272c19:dd:d9:dd:c25:dd0:dd08:3039
302c19:dd:d9:dd:c25:dd0:dd08:303a/1272c19:dd:d9:dd:c25:dd0:dd08:303b
312c19:dd:d9:dd:c25:dd0:dd08:303c/1272c19:dd:d9:dd:c25:dd0:dd08:303d
322c19:dd:d9:dd:c25:dd0:dd08:303e/1272c19:dd:d9:dd:c25:dd0:dd08:303f
332c19:dd:d9:dd:c25:dd0:dd08:3040/1272c19:dd:d9:dd:c25:dd0:dd08:3041
342c19:dd:d9:dd:c25:dd0:dd08:3042/1272c19:dd:d9:dd:c25:dd0:dd08:3043
352c19:dd:d9:dd:c25:dd0:dd08:3044/1272c19:dd:d9:dd:c25:dd0:dd08:3045
362c19:dd:d9:dd:c25:dd0:dd08:3046/1272c19:dd:d9:dd:c25:dd0:dd08:3047
372c19:dd:d9:dd:c25:dd0:dd08:3048/1272c19:dd:d9:dd:c25:dd0:dd08:3049
382c19:dd:d9:dd:c25:dd0:dd08:304a/1272c19:dd:d9:dd:c25:dd0:dd08:304b
392c19:dd:d9:dd:c25:dd0:dd08:304c/1272c19:dd:d9:dd:c25:dd0:dd08:304d
402c19:dd:d9:dd:c25:dd0:dd08:304e/1272c19:dd:d9:dd:c25:dd0:dd08:304f
412c19:dd:d9:dd:c25:dd0:dd08:3050/1272c19:dd:d9:dd:c25:dd0:dd08:3051
422c19:dd:d9:dd:c25:dd0:dd08:3052/1272c19:dd:d9:dd:c25:dd0:dd08:3053
432c19:dd:d9:dd:c25:dd0:dd08:3054/1272c19:dd:d9:dd:c25:dd0:dd08:3055
442c19:dd:d9:dd:c25:dd0:dd08:3056/1272c19:dd:d9:dd:c25:dd0:dd08:3057
452c19:dd:d9:dd:c25:dd0:dd08:3058/1272c19:dd:d9:dd:c25:dd0:dd08:3059
462c19:dd:d9:dd:c25:dd0:dd08:305a/1272c19:dd:d9:dd:c25:dd0:dd08:305b
472c19:dd:d9:dd:c25:dd0:dd08:305c/1272c19:dd:d9:dd:c25:dd0:dd08:305d
482c19:dd:d9:dd:c25:dd0:dd08:305e/1272c19:dd:d9:dd:c25:dd0:dd08:305f
492c19:dd:d9:dd:c25:dd0:dd08:3060/1272c19:dd:d9:dd:c25:dd0:dd08:3061
502c19:dd:d9:dd:c25:dd0:dd08:3062/1272c19:dd:d9:dd:c25:dd0:dd08:3063
512c19:dd:d9:dd:c25:dd0:dd08:3064/1272c19:dd:d9:dd:c25:dd0:dd08:3065
522c19:dd:d9:dd:c25:dd0:dd08:3066/1272c19:dd:d9:dd:c25:dd0:dd08:3067
532c19:dd:d9:dd:c25:dd0:dd08:3068/1272c19:dd:d9:dd:c25:dd0:dd08:3069
542c19:dd:d9:dd:c25:dd0:dd08:306a/1272c19:dd:d9:dd:c25:dd0:dd08:306b
552c19:dd:d9:dd:c25:dd0:dd08:306c/1272c19:dd:d9:dd:c25:dd0:dd08:306d
562c19:dd:d9:dd:c25:dd0:dd08:306e/1272c19:dd:d9:dd:c25:dd0:dd08:306f
572c19:dd:d9:dd:c25:dd0:dd08:3070/1272c19:dd:d9:dd:c25:dd0:dd08:3071
582c19:dd:d9:dd:c25:dd0:dd08:3072/1272c19:dd:d9:dd:c25:dd0:dd08:3073
592c19:dd:d9:dd:c25:dd0:dd08:3074/1272c19:dd:d9:dd:c25:dd0:dd08:3075
602c19:dd:d9:dd:c25:dd0:dd08:3076/1272c19:dd:d9:dd:c25:dd0:dd08:3077
612c19:dd:d9:dd:c25:dd0:dd08:3078/1272c19:dd:d9:dd:c25:dd0:dd08:3079
622c19:dd:d9:dd:c25:dd0:dd08:307a/1272c19:dd:d9:dd:c25:dd0:dd08:307b
632c19:dd:d9:dd:c25:dd0:dd08:307c/1272c19:dd:d9:dd:c25:dd0:dd08:307d
642c19:dd:d9:dd:c25:dd0:dd08:307e/1272c19:dd:d9:dd:c25:dd0:dd08:307f
652c19:dd:d9:dd:c25:dd0:dd08:3080/1272c19:dd:d9:dd:c25:dd0:dd08:3081
662c19:dd:d9:dd:c25:dd0:dd08:3082/1272c19:dd:d9:dd:c25:dd0:dd08:3083
672c19:dd:d9:dd:c25:dd0:dd08:3084/1272c19:dd:d9:dd:c25:dd0:dd08:3085
682c19:dd:d9:dd:c25:dd0:dd08:3086/1272c19:dd:d9:dd:c25:dd0:dd08:3087
692c19:dd:d9:dd:c25:dd0:dd08:3088/1272c19:dd:d9:dd:c25:dd0:dd08:3089
702c19:dd:d9:dd:c25:dd0:dd08:308a/1272c19:dd:d9:dd:c25:dd0:dd08:308b
712c19:dd:d9:dd:c25:dd0:dd08:308c/1272c19:dd:d9:dd:c25:dd0:dd08:308d
722c19:dd:d9:dd:c25:dd0:dd08:308e/1272c19:dd:d9:dd:c25:dd0:dd08:308f
732c19:dd:d9:dd:c25:dd0:dd08:3090/1272c19:dd:d9:dd:c25:dd0:dd08:3091
742c19:dd:d9:dd:c25:dd0:dd08:3092/1272c19:dd:d9:dd:c25:dd0:dd08:3093
752c19:dd:d9:dd:c25:dd0:dd08:3094/1272c19:dd:d9:dd:c25:dd0:dd08:3095
762c19:dd:d9:dd:c25:dd0:dd08:3096/1272c19:dd:d9:dd:c25:dd0:dd08:3097
772c19:dd:d9:dd:c25:dd0:dd08:3098/1272c19:dd:d9:dd:c25:dd0:dd08:3099
782c19:dd:d9:dd:c25:dd0:dd08:309a/1272c19:dd:d9:dd:c25:dd0:dd08:309b
792c19:dd:d9:dd:c25:dd0:dd08:309c/1272c19:dd:d9:dd:c25:dd0:dd08:309d
802c19:dd:d9:dd:c25:dd0:dd08:309e/1272c19:dd:d9:dd:c25:dd0:dd08:309f
812c19:dd:d9:dd:c25:dd0:dd08:30a0/1272c19:dd:d9:dd:c25:dd0:dd08:30a1
822c19:dd:d9:dd:c25:dd0:dd08:30a2/1272c19:dd:d9:dd:c25:dd0:dd08:30a3
832c19:dd:d9:dd:c25:dd0:dd08:30a4/1272c19:dd:d9:dd:c25:dd0:dd08:30a5
842c19:dd:d9:dd:c25:dd0:dd08:30a6/1272c19:dd:d9:dd:c25:dd0:dd08:30a7
852c19:dd:d9:dd:c25:dd0:dd08:30a8/1272c19:dd:d9:dd:c25:dd0:dd08:30a9
862c19:dd:d9:dd:c25:dd0:dd08:30aa/1272c19:dd:d9:dd:c25:dd0:dd08:30ab
872c19:dd:d9:dd:c25:dd0:dd08:30ac/1272c19:dd:d9:dd:c25:dd0:dd08:30ad
882c19:dd:d9:dd:c25:dd0:dd08:30ae/1272c19:dd:d9:dd:c25:dd0:dd08:30af
892c19:dd:d9:dd:c25:dd0:dd08:30b0/1272c19:dd:d9:dd:c25:dd0:dd08:30b1
902c19:dd:d9:dd:c25:dd0:dd08:30b2/1272c19:dd:d9:dd:c25:dd0:dd08:30b3
912c19:dd:d9:dd:c25:dd0:dd08:30b4/1272c19:dd:d9:dd:c25:dd0:dd08:30b5
922c19:dd:d9:dd:c25:dd0:dd08:30b6/1272c19:dd:d9:dd:c25:dd0:dd08:30b7
932c19:dd:d9:dd:c25:dd0:dd08:30b8/1272c19:dd:d9:dd:c25:dd0:dd08:30b9
942c19:dd:d9:dd:c25:dd0:dd08:30ba/1272c19:dd:d9:dd:c25:dd0:dd08:30bb
952c19:dd:d9:dd:c25:dd0:dd08:30bc/1272c19:dd:d9:dd:c25:dd0:dd08:30bd
962c19:dd:d9:dd:c25:dd0:dd08:30be/1272c19:dd:d9:dd:c25:dd0:dd08:30bf
972c19:dd:d9:dd:c25:dd0:dd08:30c0/1272c19:dd:d9:dd:c25:dd0:dd08:30c1
982c19:dd:d9:dd:c25:dd0:dd08:30c2/1272c19:dd:d9:dd:c25:dd0:dd08:30c3
992c19:dd:d9:dd:c25:dd0:dd08:30c4/1272c19:dd:d9:dd:c25:dd0:dd08:30c5
1002c19:dd:d9:dd:c25:dd0:dd08:30c6/1272c19:dd:d9:dd:c25:dd0:dd08:30c7
1012c19:dd:d9:dd:c25:dd0:dd08:30c8/1272c19:dd:d9:dd:c25:dd0:dd08:30c9
1022c19:dd:d9:dd:c25:dd0:dd08:30ca/1272c19:dd:d9:dd:c25:dd0:dd08:30cb
1032c19:dd:d9:dd:c25:dd0:dd08:30cc/1272c19:dd:d9:dd:c25:dd0:dd08:30cd
1042c19:dd:d9:dd:c25:dd0:dd08:30ce/1272c19:dd:d9:dd:c25:dd0:dd08:30cf
1052c19:dd:d9:dd:c25:dd0:dd08:30d0/1272c19:dd:d9:dd:c25:dd0:dd08:30d1
1062c19:dd:d9:dd:c25:dd0:dd08:30d2/1272c19:dd:d9:dd:c25:dd0:dd08:30d3
1072c19:dd:d9:dd:c25:dd0:dd08:30d4/1272c19:dd:d9:dd:c25:dd0:dd08:30d5
1082c19:dd:d9:dd:c25:dd0:dd08:30d6/1272c19:dd:d9:dd:c25:dd0:dd08:30d7
1092c19:dd:d9:dd:c25:dd0:dd08:30d8/1272c19:dd:d9:dd:c25:dd0:dd08:30d9
1102c19:dd:d9:dd:c25:dd0:dd08:30da/1272c19:dd:d9:dd:c25:dd0:dd08:30db
1112c19:dd:d9:dd:c25:dd0:dd08:30dc/1272c19:dd:d9:dd:c25:dd0:dd08:30dd
1122c19:dd:d9:dd:c25:dd0:dd08:30de/1272c19:dd:d9:dd:c25:dd0:dd08:30df
1132c19:dd:d9:dd:c25:dd0:dd08:30e0/1272c19:dd:d9:dd:c25:dd0:dd08:30e1
1142c19:dd:d9:dd:c25:dd0:dd08:30e2/1272c19:dd:d9:dd:c25:dd0:dd08:30e3
1152c19:dd:d9:dd:c25:dd0:dd08:30e4/1272c19:dd:d9:dd:c25:dd0:dd08:30e5
1162c19:dd:d9:dd:c25:dd0:dd08:30e6/1272c19:dd:d9:dd:c25:dd0:dd08:30e7
1172c19:dd:d9:dd:c25:dd0:dd08:30e8/1272c19:dd:d9:dd:c25:dd0:dd08:30e9
1182c19:dd:d9:dd:c25:dd0:dd08:30ea/1272c19:dd:d9:dd:c25:dd0:dd08:30eb
1192c19:dd:d9:dd:c25:dd0:dd08:30ec/1272c19:dd:d9:dd:c25:dd0:dd08:30ed
1202c19:dd:d9:dd:c25:dd0:dd08:30ee/1272c19:dd:d9:dd:c25:dd0:dd08:30ef
1212c19:dd:d9:dd:c25:dd0:dd08:30f0/1272c19:dd:d9:dd:c25:dd0:dd08:30f1
1222c19:dd:d9:dd:c25:dd0:dd08:30f2/1272c19:dd:d9:dd:c25:dd0:dd08:30f3
1232c19:dd:d9:dd:c25:dd0:dd08:30f4/1272c19:dd:d9:dd:c25:dd0:dd08:30f5
1242c19:dd:d9:dd:c25:dd0:dd08:30f6/1272c19:dd:d9:dd:c25:dd0:dd08:30f7
1252c19:dd:d9:dd:c25:dd0:dd08:30f8/1272c19:dd:d9:dd:c25:dd0:dd08:30f9
1262c19:dd:d9:dd:c25:dd0:dd08:30fa/1272c19:dd:d9:dd:c25:dd0:dd08:30fb
1272c19:dd:d9:dd:c25:dd0:dd08:30fc/1272c19:dd:d9:dd:c25:dd0:dd08:30fd
1282c19:dd:d9:dd:c25:dd0:dd08:30fe/1272c19:dd:d9:dd:c25:dd0:dd08:30ff
1292c19:dd:d9:dd:c25:dd0:dd08:3100/1272c19:dd:d9:dd:c25:dd0:dd08:3101
1302c19:dd:d9:dd:c25:dd0:dd08:3102/1272c19:dd:d9:dd:c25:dd0:dd08:3103
1312c19:dd:d9:dd:c25:dd0:dd08:3104/1272c19:dd:d9:dd:c25:dd0:dd08:3105
1322c19:dd:d9:dd:c25:dd0:dd08:3106/1272c19:dd:d9:dd:c25:dd0:dd08:3107
1332c19:dd:d9:dd:c25:dd0:dd08:3108/1272c19:dd:d9:dd:c25:dd0:dd08:3109
1342c19:dd:d9:dd:c25:dd0:dd08:310a/1272c19:dd:d9:dd:c25:dd0:dd08:310b
1352c19:dd:d9:dd:c25:dd0:dd08:310c/1272c19:dd:d9:dd:c25:dd0:dd08:310d
1362c19:dd:d9:dd:c25:dd0:dd08:310e/1272c19:dd:d9:dd:c25:dd0:dd08:310f
1372c19:dd:d9:dd:c25:dd0:dd08:3110/1272c19:dd:d9:dd:c25:dd0:dd08:3111
1382c19:dd:d9:dd:c25:dd0:dd08:3112/1272c19:dd:d9:dd:c25:dd0:dd08:3113
1392c19:dd:d9:dd:c25:dd0:dd08:3114/1272c19:dd:d9:dd:c25:dd0:dd08:3115
1402c19:dd:d9:dd:c25:dd0:dd08:3116/1272c19:dd:d9:dd:c25:dd0:dd08:3117
1412c19:dd:d9:dd:c25:dd0:dd08:3118/1272c19:dd:d9:dd:c25:dd0:dd08:3119
1422c19:dd:d9:dd:c25:dd0:dd08:311a/1272c19:dd:d9:dd:c25:dd0:dd08:311b
1432c19:dd:d9:dd:c25:dd0:dd08:311c/1272c19:dd:d9:dd:c25:dd0:dd08:311d
1442c19:dd:d9:dd:c25:dd0:dd08:311e/1272c19:dd:d9:dd:c25:dd0:dd08:311f
1452c19:dd:d9:dd:c25:dd0:dd08:3120/1272c19:dd:d9:dd:c25:dd0:dd08:3121
1462c19:dd:d9:dd:c25:dd0:dd08:3122/1272c19:dd:d9:dd:c25:dd0:dd08:3123
1472c19:dd:d9:dd:c25:dd0:dd08:3124/1272c19:dd:d9:dd:c25:dd0:dd08:3125
1482c19:dd:d9:dd:c25:dd0:dd08:3126/1272c19:dd:d9:dd:c25:dd0:dd08:3127
1492c19:dd:d9:dd:c25:dd0:dd08:3128/1272c19:dd:d9:dd:c25:dd0:dd08:3129
1502c19:dd:d9:dd:c25:dd0:dd08:312a/1272c19:dd:d9:dd:c25:dd0:dd08:312b
1512c19:dd:d9:dd:c25:dd0:dd08:312c/1272c19:dd:d9:dd:c25:dd0:dd08:312d
1522c19:dd:d9:dd:c25:dd0:dd08:312e/1272c19:dd:d9:dd:c25:dd0:dd08:312f
1532c19:dd:d9:dd:c25:dd0:dd08:3130/1272c19:dd:d9:dd:c25:dd0:dd08:3131
1542c19:dd:d9:dd:c25:dd0:dd08:3132/1272c19:dd:d9:dd:c25:dd0:dd08:3133
1552c19:dd:d9:dd:c25:dd0:dd08:3134/1272c19:dd:d9:dd:c25:dd0:dd08:3135
1562c19:dd:d9:dd:c25:dd0:dd08:3136/1272c19:dd:d9:dd:c25:dd0:dd08:3137
1572c19:dd:d9:dd:c25:dd0:dd08:3138/1272c19:dd:d9:dd:c25:dd0:dd08:3139
1582c19:dd:d9:dd:c25:dd0:dd08:313a/1272c19:dd:d9:dd:c25:dd0:dd08:313b
1592c19:dd:d9:dd:c25:dd0:dd08:313c/1272c19:dd:d9:dd:c25:dd0:dd08:313d
1602c19:dd:d9:dd:c25:dd0:dd08:313e/1272c19:dd:d9:dd:c25:dd0:dd08:313f
1612c19:dd:d9:dd:c25:dd0:dd08:3140/1272c19:dd:d9:dd:c25:dd0:dd08:3141
1622c19:dd:d9:dd:c25:dd0:dd08:3142/1272c19:dd:d9:dd:c25:dd0:dd08:3143
1632c19:dd:d9:dd:c25:dd0:dd08:3144/1272c19:dd:d9:dd:c25:dd0:dd08:3145
1642c19:dd:d9:dd:c25:dd0:dd08:3146/1272c19:dd:d9:dd:c25:dd0:dd08:3147
1652c19:dd:d9:dd:c25:dd0:dd08:3148/1272c19:dd:d9:dd:c25:dd0:dd08:3149
1662c19:dd:d9:dd:c25:dd0:dd08:314a/1272c19:dd:d9:dd:c25:dd0:dd08:314b
1672c19:dd:d9:dd:c25:dd0:dd08:314c/1272c19:dd:d9:dd:c25:dd0:dd08:314d
1682c19:dd:d9:dd:c25:dd0:dd08:314e/1272c19:dd:d9:dd:c25:dd0:dd08:314f
1692c19:dd:d9:dd:c25:dd0:dd08:3150/1272c19:dd:d9:dd:c25:dd0:dd08:3151
1702c19:dd:d9:dd:c25:dd0:dd08:3152/1272c19:dd:d9:dd:c25:dd0:dd08:3153
1712c19:dd:d9:dd:c25:dd0:dd08:3154/1272c19:dd:d9:dd:c25:dd0:dd08:3155
1722c19:dd:d9:dd:c25:dd0:dd08:3156/1272c19:dd:d9:dd:c25:dd0:dd08:3157
1732c19:dd:d9:dd:c25:dd0:dd08:3158/1272c19:dd:d9:dd:c25:dd0:dd08:3159
1742c19:dd:d9:dd:c25:dd0:dd08:315a/1272c19:dd:d9:dd:c25:dd0:dd08:315b
1752c19:dd:d9:dd:c25:dd0:dd08:315c/1272c19:dd:d9:dd:c25:dd0:dd08:315d
1762c19:dd:d9:dd:c25:dd0:dd08:315e/1272c19:dd:d9:dd:c25:dd0:dd08:315f
1772c19:dd:d9:dd:c25:dd0:dd08:3160/1272c19:dd:d9:dd:c25:dd0:dd08:3161
1782c19:dd:d9:dd:c25:dd0:dd08:3162/1272c19:dd:d9:dd:c25:dd0:dd08:3163
1792c19:dd:d9:dd:c25:dd0:dd08:3164/1272c19:dd:d9:dd:c25:dd0:dd08:3165
1802c19:dd:d9:dd:c25:dd0:dd08:3166/1272c19:dd:d9:dd:c25:dd0:dd08:3167
1812c19:dd:d9:dd:c25:dd0:dd08:3168/1272c19:dd:d9:dd:c25:dd0:dd08:3169
1822c19:dd:d9:dd:c25:dd0:dd08:316a/1272c19:dd:d9:dd:c25:dd0:dd08:316b
1832c19:dd:d9:dd:c25:dd0:dd08:316c/1272c19:dd:d9:dd:c25:dd0:dd08:316d
1842c19:dd:d9:dd:c25:dd0:dd08:316e/1272c19:dd:d9:dd:c25:dd0:dd08:316f
1852c19:dd:d9:dd:c25:dd0:dd08:3170/1272c19:dd:d9:dd:c25:dd0:dd08:3171
1862c19:dd:d9:dd:c25:dd0:dd08:3172/1272c19:dd:d9:dd:c25:dd0:dd08:3173
1872c19:dd:d9:dd:c25:dd0:dd08:3174/1272c19:dd:d9:dd:c25:dd0:dd08:3175
1882c19:dd:d9:dd:c25:dd0:dd08:3176/1272c19:dd:d9:dd:c25:dd0:dd08:3177
1892c19:dd:d9:dd:c25:dd0:dd08:3178/1272c19:dd:d9:dd:c25:dd0:dd08:3179
1902c19:dd:d9:dd:c25:dd0:dd08:317a/1272c19:dd:d9:dd:c25:dd0:dd08:317b
1912c19:dd:d9:dd:c25:dd0:dd08:317c/1272c19:dd:d9:dd:c25:dd0:dd08:317d
1922c19:dd:d9:dd:c25:dd0:dd08:317e/1272c19:dd:d9:dd:c25:dd0:dd08:317f
1932c19:dd:d9:dd:c25:dd0:dd08:3180/1272c19:dd:d9:dd:c25:dd0:dd08:3181
1942c19:dd:d9:dd:c25:dd0:dd08:3182/1272c19:dd:d9:dd:c25:dd0:dd08:3183
1952c19:dd:d9:dd:c25:dd0:dd08:3184/1272c19:dd:d9:dd:c25:dd0:dd08:3185
1962c19:dd:d9:dd:c25:dd0:dd08:3186/1272c19:dd:d9:dd:c25:dd0:dd08:3187
1972c19:dd:d9:dd:c25:dd0:dd08:3188/1272c19:dd:d9:dd:c25:dd0:dd08:3189
1982c19:dd:d9:dd:c25:dd0:dd08:318a/1272c19:dd:d9:dd:c25:dd0:dd08:318b
1992c19:dd:d9:dd:c25:dd0:dd08:318c/1272c19:dd:d9:dd:c25:dd0:dd08:318d
2002c19:dd:d9:dd:c25:dd0:dd08:318e/1272c19:dd:d9:dd:c25:dd0:dd08:318f
2012c19:dd:d9:dd:c25:dd0:dd08:3190/1272c19:dd:d9:dd:c25:dd0:dd08:3191
2022c19:dd:d9:dd:c25:dd0:dd08:3192/1272c19:dd:d9:dd:c25:dd0:dd08:3193
2032c19:dd:d9:dd:c25:dd0:dd08:3194/1272c19:dd:d9:dd:c25:dd0:dd08:3195
2042c19:dd:d9:dd:c25:dd0:dd08:3196/1272c19:dd:d9:dd:c25:dd0:dd08:3197
2052c19:dd:d9:dd:c25:dd0:dd08:3198/1272c19:dd:d9:dd:c25:dd0:dd08:3199
2062c19:dd:d9:dd:c25:dd0:dd08:319a/1272c19:dd:d9:dd:c25:dd0:dd08:319b
2072c19:dd:d9:dd:c25:dd0:dd08:319c/1272c19:dd:d9:dd:c25:dd0:dd08:319d
2082c19:dd:d9:dd:c25:dd0:dd08:319e/1272c19:dd:d9:dd:c25:dd0:dd08:319f
2092c19:dd:d9:dd:c25:dd0:dd08:31a0/1272c19:dd:d9:dd:c25:dd0:dd08:31a1
2102c19:dd:d9:dd:c25:dd0:dd08:31a2/1272c19:dd:d9:dd:c25:dd0:dd08:31a3
2112c19:dd:d9:dd:c25:dd0:dd08:31a4/1272c19:dd:d9:dd:c25:dd0:dd08:31a5
2122c19:dd:d9:dd:c25:dd0:dd08:31a6/1272c19:dd:d9:dd:c25:dd0:dd08:31a7
2132c19:dd:d9:dd:c25:dd0:dd08:31a8/1272c19:dd:d9:dd:c25:dd0:dd08:31a9
2142c19:dd:d9:dd:c25:dd0:dd08:31aa/1272c19:dd:d9:dd:c25:dd0:dd08:31ab
2152c19:dd:d9:dd:c25:dd0:dd08:31ac/1272c19:dd:d9:dd:c25:dd0:dd08:31ad
2162c19:dd:d9:dd:c25:dd0:dd08:31ae/1272c19:dd:d9:dd:c25:dd0:dd08:31af
2172c19:dd:d9:dd:c25:dd0:dd08:31b0/1272c19:dd:d9:dd:c25:dd0:dd08:31b1
2182c19:dd:d9:dd:c25:dd0:dd08:31b2/1272c19:dd:d9:dd:c25:dd0:dd08:31b3
2192c19:dd:d9:dd:c25:dd0:dd08:31b4/1272c19:dd:d9:dd:c25:dd0:dd08:31b5
2202c19:dd:d9:dd:c25:dd0:dd08:31b6/1272c19:dd:d9:dd:c25:dd0:dd08:31b7
2212c19:dd:d9:dd:c25:dd0:dd08:31b8/1272c19:dd:d9:dd:c25:dd0:dd08:31b9
2222c19:dd:d9:dd:c25:dd0:dd08:31ba/1272c19:dd:d9:dd:c25:dd0:dd08:31bb
2232c19:dd:d9:dd:c25:dd0:dd08:31bc/1272c19:dd:d9:dd:c25:dd0:dd08:31bd
2242c19:dd:d9:dd:c25:dd0:dd08:31be/1272c19:dd:d9:dd:c25:dd0:dd08:31bf
2252c19:dd:d9:dd:c25:dd0:dd08:31c0/1272c19:dd:d9:dd:c25:dd0:dd08:31c1
2262c19:dd:d9:dd:c25:dd0:dd08:31c2/1272c19:dd:d9:dd:c25:dd0:dd08:31c3
2272c19:dd:d9:dd:c25:dd0:dd08:31c4/1272c19:dd:d9:dd:c25:dd0:dd08:31c5
2282c19:dd:d9:dd:c25:dd0:dd08:31c6/1272c19:dd:d9:dd:c25:dd0:dd08:31c7
2292c19:dd:d9:dd:c25:dd0:dd08:31c8/1272c19:dd:d9:dd:c25:dd0:dd08:31c9
2302c19:dd:d9:dd:c25:dd0:dd08:31ca/1272c19:dd:d9:dd:c25:dd0:dd08:31cb
2312c19:dd:d9:dd:c25:dd0:dd08:31cc/1272c19:dd:d9:dd:c25:dd0:dd08:31cd
2322c19:dd:d9:dd:c25:dd0:dd08:31ce/1272c19:dd:d9:dd:c25:dd0:dd08:31cf
2332c19:dd:d9:dd:c25:dd0:dd08:31d0/1272c19:dd:d9:dd:c25:dd0:dd08:31d1
2342c19:dd:d9:dd:c25:dd0:dd08:31d2/1272c19:dd:d9:dd:c25:dd0:dd08:31d3
2352c19:dd:d9:dd:c25:dd0:dd08:31d4/1272c19:dd:d9:dd:c25:dd0:dd08:31d5
2362c19:dd:d9:dd:c25:dd0:dd08:31d6/1272c19:dd:d9:dd:c25:dd0:dd08:31d7
2372c19:dd:d9:dd:c25:dd0:dd08:31d8/1272c19:dd:d9:dd:c25:dd0:dd08:31d9
2382c19:dd:d9:dd:c25:dd0:dd08:31da/1272c19:dd:d9:dd:c25:dd0:dd08:31db
2392c19:dd:d9:dd:c25:dd0:dd08:31dc/1272c19:dd:d9:dd:c25:dd0:dd08:31dd
2402c19:dd:d9:dd:c25:dd0:dd08:31de/1272c19:dd:d9:dd:c25:dd0:dd08:31df
2412c19:dd:d9:dd:c25:dd0:dd08:31e0/1272c19:dd:d9:dd:c25:dd0:dd08:31e1
2422c19:dd:d9:dd:c25:dd0:dd08:31e2/1272c19:dd:d9:dd:c25:dd0:dd08:31e3
2432c19:dd:d9:dd:c25:dd0:dd08:31e4/1272c19:dd:d9:dd:c25:dd0:dd08:31e5
2442c19:dd:d9:dd:c25:dd0:dd08:31e6/1272c19:dd:d9:dd:c25:dd0:dd08:31e7
2452c19:dd:d9:dd:c25:dd0:dd08:31e8/1272c19:dd:d9:dd:c25:dd0:dd08:31e9
2462c19:dd:d9:dd:c25:dd0:dd08:31ea/1272c19:dd:d9:dd:c25:dd0:dd08:31eb
2472c19:dd:d9:dd:c25:dd0:dd08:31ec/1272c19:dd:d9:dd:c25:dd0:dd08:31ed
2482c19:dd:d9:dd:c25:dd0:dd08:31ee/1272c19:dd:d9:dd:c25:dd0:dd08:31ef
2492c19:dd:d9:dd:c25:dd0:dd08:31f0/1272c19:dd:d9:dd:c25:dd0:dd08:31f1
2502c19:dd:d9:dd:c25:dd0:dd08:31f2/1272c19:dd:d9:dd:c25:dd0:dd08:31f3
2512c19:dd:d9:dd:c25:dd0:dd08:31f4/1272c19:dd:d9:dd:c25:dd0:dd08:31f5
2522c19:dd:d9:dd:c25:dd0:dd08:31f6/1272c19:dd:d9:dd:c25:dd0:dd08:31f7
2532c19:dd:d9:dd:c25:dd0:dd08:31f8/1272c19:dd:d9:dd:c25:dd0:dd08:31f9
2542c19:dd:d9:dd:c25:dd0:dd08:31fa/1272c19:dd:d9:dd:c25:dd0:dd08:31fb
2552c19:dd:d9:dd:c25:dd0:dd08:31fc/1272c19:dd:d9:dd:c25:dd0:dd08:31fd
2562c19:dd:d9:dd:c25:dd0:dd08:31fe/1272c19:dd:d9:dd:c25:dd0:dd08:31ff

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.