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If DNS went down

CalderCalder Member Posts: 15 ■□□□□□□□□□
in CCNA & CCENT
I got a question
Lets say all DNS servers over the world went down and you knew the ip address to youtubes's homepage, would you be able to watch videos on the site? because as far as i know they are on a different Url to the mainpage so would your pc try to find an ip to the url or is there some sort of indexing that goes on therefore making you able to watch the video, or something different altogether?
If you know please enlighten me :P
Thanks
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    PashPash Member Posts: 1,600 ■■■■■□□□□□
    If in the case you are refering to you browsed to http://xxx.xxx.xxx.xxx (which collates to YouTube - Broadcast Yourself.) and then clicked on a video link on the homepage it would try to use the relative link value something like http://www.youtube.com/video+id=780808. Aslong as you know the top level domain ip for youtube.com you could just swap that out on every page you visited, some browsers even have mods or options to do this but the whole point of DNS is to turn computer like ip addresses into human like words. Only us in IT are meant to remember IP addresses ;)
    DevOps Engineer and Security Champion. https://blog.pash.by - I am trying to find my writing style, so please bear with me.
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    dynamikdynamik Banned Posts: 12,312 ■■■■■■■■■□
    The big problem you'd have is for sites that use shared hosting (multiple domains assigned to one IP) because it uses the domain name to determine which site you want to visit.
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    PashPash Member Posts: 1,600 ■■■■■□□□□□
    dynamik wrote: »
    The big problem you'd have is for sites that use shared hosting (multiple domains assigned to one IP) because it uses the domain name to determine which site you want to visit.

    This is also a very good point.
    DevOps Engineer and Security Champion. https://blog.pash.by - I am trying to find my writing style, so please bear with me.
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    tierstentiersten Member Posts: 4,505
    dynamik wrote: »
    The big problem you'd have is for sites that use shared hosting (multiple domains assigned to one IP) because it uses the domain name to determine which site you want to visit.
    It works it out by you sending it a Host header in the request. You'd still be able to access those sites. Its just whether your browser supports the ability for you to specify an IP address and a host header separately.

    If all else fails then use telnet and get good at visualising HTML ;)
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    PashPash Member Posts: 1,600 ■■■■■□□□□□
    tiersten wrote: »
    It works it out by you sending it a Host header in the request. You'd still be able to access those sites. Its just whether your browser supports the ability for you to specify an IP address and a host header separately.

    If all else fails then use telnet and get good at visualising HTML ;)

    The point has been bettered! i guess by adding the hhv to the url requests you can hit the different websites.
    DevOps Engineer and Security Champion. https://blog.pash.by - I am trying to find my writing style, so please bear with me.
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    captobviouscaptobvious Member Posts: 648
    Calder wrote: »
    I got a question
    Lets say all DNS servers over the world went down .....

    I'd blame Bill Gates and his posse! :o
    WIP
    CCNA:S

    Don't be a dumper!
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    wedge1988wedge1988 Member Posts: 434 ■■■□□□□□□□
    Im not sure about this one, but if public DNS servers do use reverse lookups then if they're down IP addresses wouldnt work. lol.
    ~ wedge1988 ~ IdioT Certified~
    MCSE:2003 ~ MCITP:EA ~ CCNP:R&S ~ CCNA:R&S ~ CCNA:Voice ~ Office 2000 MASTER ~ A+ ~ N+ ~ C&G:IT Diploma ~ Ofqual Entry Japanese
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    tierstentiersten Member Posts: 4,505
    wedge1988 wrote: »
    Im not sure about this one, but if public DNS servers do use reverse lookups then if they're down IP addresses wouldnt work. lol.
    No. IP addresses would still work.
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    wedge1988wedge1988 Member Posts: 434 ■■■□□□□□□□
    tiersten wrote: »
    No. IP addresses would still work.

    why's this then? Im a bit confused now, unless im missing something blatantly obvious.

    Is it something to do with routing tables?
    ~ wedge1988 ~ IdioT Certified~
    MCSE:2003 ~ MCITP:EA ~ CCNP:R&S ~ CCNA:R&S ~ CCNA:Voice ~ Office 2000 MASTER ~ A+ ~ N+ ~ C&G:IT Diploma ~ Ofqual Entry Japanese
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    tierstentiersten Member Posts: 4,505
    wedge1988 wrote: »
    why's this then? Im a bit confused now, unless im missing something blatantly obvious.

    Is it something to do with routing tables?
    Routing is done with the IP address only. DNS is mainly for the benefit of humans. A reverse lookup is finding out if somebody has assigned a name to that IP address. It again is for humans.

    Think of DNS as a phonebook. If you want to call somebody then you'd go look them up and then dial the number. If you lost your phonebook later on but still remembered the number then you can just dial it. If you lost your phonebook and wanted to call somebody new then you'd be stuck. The phonebook isn't vital if you know the numbers already.
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