Longest Possible Domain Name

http://a.b.c.d.e.f.g.h.i.j.k.l.m.n.oo.pp.qqq.rrrr.ssssss.tttttttt.uuuuuuuuuuu.vvvvvvvvvvvvvvv.wwwwwwwwwwwwwwwwwwwwww.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy.zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz.me

by phil294 • 5 years ago

26 19 5 years ago

a.b.c.d.e.f.g.h.i.j.k.l.m.n.oo.pp.qqq.rrrr.ssssss.tttttttt.uuuuuuuuuuu.vvvvvvvvvvvvvvv.wwwwwwwwwwwwwwwwwwwwww.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy.zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz.me

Stevvo• 5 years ago

Not very long, as z is a pretty short character.

httpsterio• 5 years ago

depends on your font, in monospace it's equally long as any other letter.

ggoo• 5 years ago

that is a long name.

emerged• 5 years ago

By number of characters maybe, but there are longer characters.

nohuck13• 5 years ago

Full domain name (since my phone and HN seem to elide it in places):

spiderice• 5 years ago

I'm on desktop and HN still crops the domain name. Here it is with spaces added to it wraps:

http://a.b.c.d.e.f.g. h.i.j.k.l.m.n.oo.pp. qqq.rrrr.ssssss.tttttttt.uuuuuuuuuuu. vvvvvvvvvvvvvvv.wwwwwwwwwwwwwwwwwwwwww. xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx. yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy. zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz zzzzzzzzzzzzzzzzzzzzzzzzzzzzzz.me

catchmeifyoucan• 5 years ago

if you use a TLD like ".motorcycles" , you could probably make it even longer

X-Istence• 5 years ago

There's a maximum limit of ~250 bytes for a DNS name.

See https://stackoverflow.com/questions/32290167/what-is-the-max... for more information.

Using a longer TLD won't change the maximum length.

rafaelturk• 5 years ago

Please add Let's Encrypt, make it secure!

schoen• 5 years ago

Amusingly, there's a backward compatibility issue where the first name on a Let's Encrypt certificate can only be, at most, 63 characters long (because it gets represented in the CN field, which is limited this way). All of the other names get represented only in SAN extensions, which don't have the same limit.

So, if you need a Let's Encrypt certificate for a name over 63 characters in length, you have to also put another name on that certificate that is shorter, so Let's Encrypt has something to put in the CN field.

Sniffnoy• 5 years ago

Unfortunately, the blog post linked to is now a 404. Here's an archived version: https://web.archive.org/web/20180202204836/http://blog.sacal...

marto1• 5 years ago

Why is it 253 and not 255 characters ? It's killing my OCD.

weitzj• 5 years ago

Random guess: Maybe because domains normally end with a dot, i.e. google.com. and maybe some termination character NULL string? 253+ 1+ 1 ?

mimimi31• 5 years ago

The domain name is transmitted as a sequence of labels plus one byte for each label's length, followed by a null byte for the root label. Everything together must fit into 255 bytes.

So the domain name x.y.z (technically x.y.z. with the empty space after the last dot representing the root label) uses the following bytes:

[length of x][x][length of y][y][length of z][z][length of root label, i.e. 0]

Since we usually add dots to visually separate labels, you can imagine the dots and inner length bytes cancelling each other out, leaving the first length byte and the last null byte as the two "missing" bytes.

wayneftw• 5 years ago

Thanks for screwing up the hckrnews interface for the next 24 hours.

RONROC• 5 years ago

I was wondering why hckrnews.com was rendering poorly on Safari (iOS). Your comment helped connect the dots.

Funny side effect!

cvhashim• 5 years ago

Gash darn it ! :(

andreineculau• 5 years ago

Or: thanks for revealing a possible improvement on hckrnews ;)

1ca• 5 years ago

In the same idea I set this up a while ago, no use of sub domains though haha: https://1111111111111111111111111111111111111111111111111111...

Longest Possible Domain Name

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