Ok, Ednilson is correct in that the list will not help Shella solve her
problem. However, I would generally take what www.iana.org says as "the
standard" that all should abide by. Does that mean people will break
it? You betcha. What kind of authority says that they are right? Well,
any good network engineer knows that RFC1918 claims a particular set of
networks are deemed for private usage. Guess who tries to mandate such
RFCs in ip address allocation and port allocation, iana.
http://www.iana.org/assignments/ipv4-address-space
The list has allocated the port, UDP and TCP for it. Yes, not every
application uses both, but they might, and that is the point. They do
preallocation for a particular protocol and people stick with those 'well
known ports' as a standard to avoid pure chaos.
In reference to Shella, the best way is unfortunately, to read the RFC for
the protocol. As far as I remember, DNS uses UDP almost exclusively for
all queries, and TCP for DNS Zone Transfers. If that does not make any
sense to you, you really should double up on the reading on DNS. For most
intents and purpose, you only really need UDP to go through unless you got
secondaries, tertiaries, quadaries (sic) sitting far and away. This is
assuming a well defined DNS server that follows the specs. I am sure you
can find deviations from the ever-so-popular microsoft DNS servers or any
other dns server. But hey, that's the price you pay for buying into the
"pioneers" of their own standards.
At 04:39 PM 8/27/01 -0400, Ednilson Rosa wrote:
>The problem with this list is that every application seem to use both UDP
>and TCP, which is not always true.
>
>Ednilson Rosa
>
>----- Original Message -----
>From: "Brian Whalen"
>To:
>Sent: Monday, August 27, 2001 5:03 PM
>Subject: Re: access-list & ports ( TCP /UDP) [7:17374]
>
>
>I use http://www.iana.org/assignments/port-numbers for finding out about
>port numbers. Re the dns topic below, udp is fine for a company that does
>not have its own dns servers and only makes queries. TCP is used for zone
>transfers. I believe that in newer versions of bind, random hi port
>numbers are used.
>
>Brian "Sonic" Whalen
>Success = Preparation + Opportunity
>
>
>On Mon, 27 Aug 2001, shella kevin wrote:
>
> > when dealing with access-list we use both TCP & UDP. For example we use
> > tcp 53 or udp 53 for domain.
> >
> > My Q is when & how we know when we should use UDP and when TCP .........
> > what is the difference .
> >
> >
> >
> > Thanks
> >
> > Shella K.
-Carroll Kong
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=17452&t=17374
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