Computer networks -- 2007-2008 -- info.uvt.ro/Course 9

These pages are somehow outdated and it is recommended to consult the newer version at Computer networks -- 2008-2009 -- info.uvt.ro (by Ciprian Crăciun).

Quick links:

front;
courses 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13;
laboratories agenda, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, evaluation, tools, repository.

OSI upper layers

Session layer

Presentation Layer

Application Layer

DNS

DNS -- Domain Name System;
purpose:
- decouple machine names from machine addresses;
- provide textual addresses for network resources;
characteristics:
- hierarchical naming scheme;
- each domain is partitioned in sub-domains;
- naming follows organizational boundaries, not physical networks;
- 200 top-level domains (generic and countries);
concepts:
- resource records:
  - domain name;
  - time to live;
  - class (IN);
  - type (A, CNAME, MX);
  - value;
- registrars;
- name servers;
- resolvers;
- recursive queries;
links:
- wikipedia:Domain Name System;

E-mail

email structure:
- header;
- body;

simple email example:

From: John Doe <jdoe@machine.example>
To: Mary Smith <mary@example.net>
Subject: Saying Hello
Date: Fri, 21 Nov 1997 09:55:06 -0600
Message-ID: <1234@local.machine.example>

This is a message just to say hello.
So, "Hello".

(real) email example:

Return-Path: ccraciun@cci.uvt.ro
Received: from hermes.info.uvt.ro (LHLO hermes.info.uvt.ro) (194.102.62.58)
 by hermes.info.uvt.ro with LMTP; Mon, 21 Apr 2008 14:42:12 +0300 (EEST)
Received: from localhost (localhost.localdomain [127.0.0.1])
	by hermes.info.uvt.ro (Postfix) with ESMTP id E0C16DE0408
	for <ccraciun@info.uvt.ro>; Mon, 21 Apr 2008 14:42:12 +0300 (EEST)
X-Virus-Scanned: amavisd-new at 
X-Spam-Flag: NO
X-Spam-Score: -2.599
X-Spam-Level: 
X-Spam-Status: No, score=-2.599 tagged_above=-10 required=6.6
	tests=[BAYES_00=-2.599]
Received: from hermes.info.uvt.ro ([127.0.0.1])
	by localhost (hermes.info.uvt.ro [127.0.0.1]) (amavisd-new, port 10024)
	with ESMTP id rLfp9GrKP-MW for <ccraciun@info.uvt.ro>;
	Mon, 21 Apr 2008 14:42:12 +0300 (EEST)
Received: from hercules.uvt.ro (mail.uvt.ro [85.120.204.100])
	by hermes.info.uvt.ro (Postfix) with SMTP id 07335DE03DF
	for <ccraciun@info.uvt.ro>; Mon, 21 Apr 2008 14:42:11 +0300 (EEST)
Received: from localhost (localhost.localdomain [127.0.0.1])
	by hercules.uvt.ro (Postfix) with ESMTP id 99EBF192D9DA
	for <ccraciun@info.uvt.ro>; Mon, 21 Apr 2008 16:20:45 +0300 (EEST)
X-Virus-Scanned: amavisd-new at 
Received: from hercules.uvt.ro ([127.0.0.1])
	by localhost (hercules.uvt.ro [127.0.0.1]) (amavisd-new, port 10024)
	with ESMTP id 3iM-RcdAq8m5 for <ccraciun@info.uvt.ro>;
	Mon, 21 Apr 2008 16:20:45 +0300 (EEST)
Received: from hercules.uvt.ro (hercules.uvt.ro [85.120.204.100])
	by hercules.uvt.ro (Postfix) with ESMTP id 3DF1B192D9D9
	for <ccraciun@info.uvt.ro>; Mon, 21 Apr 2008 16:20:45 +0300 (EEST)
Date: Mon, 21 Apr 2008 16:20:45 +0300 (EEST)
From: Craciun Ciprian Dorin <ccraciun@cci.uvt.ro>
To: ccraciun@info.uvt.ro
Message-ID: <1385273071.10131208784045168.JavaMail.root@hercules.uvt.ro>
Subject: Test e-mail
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
X-Originating-IP: [194.102.62.253]

This is a simple test e-mail.