Domain Name System WWW. Application Layer. Mahalingam Ramkumar Mississippi State University, MS. September 15, 2014.

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "Domain Name System E-mail WWW. Application Layer. Mahalingam Ramkumar Mississippi State University, MS. September 15, 2014."

Transcription

1 Application Layer Mahalingam Mississippi State University, MS September 15, 2014

2 Outline 1 DNS Records DNS Components 2 Message Transfer Fetching s 3

3 Applications We will focus on 3 applications DNS

4 Domain Name Space DNS Records DNS Components Generic Countries int com edu gov mil org net jp us nl... sun yale acm ieee ac co oce vu eng cs eng jack jill keio nec cs ai linda cs csl flits fluit robot pc24

5 Domain Name Space DNS Records DNS Components DNS Root at the top of the inverted tree Top level domains generic (gtld) and country-code (cctld) New TLDs added rarely Names below TLDs can be purchased (if available) DNS is a distributed database of DNS records A database for every zone

6 Domain Name Service DNS Records DNS Components DNS (domain name service) provides domain-name to IP look-up Naming according to organizational boundaries - not physical IP addresses depend on physical location (issued by a ISP) DNS is an application uses UDP as the transport layer DNS servers queried by DNS clients.

7 DNS Zone DNS Records DNS Components name under the control of an entity msstate.edu is a zone Owner of zone msstate.edu authorized to create any name ending with msstate.edu. Can also delegate some names to other entities For example, cse.msstate.edu has been delegated A delegated name becomes a zone Root delegated gtld edu. gtld edu delegated msstate.edu. msstate.edu delegated cse.msstate.edu need not delegate all names (for example, eng.msstate.edu is not delegated, and so is still under the control of msstate.edu.

8 DNS Database DNS Records DNS Components Zone owner responsible for creating the zone database Zone database (or zone file, or, zone master file) is a list of DNS records Each record indicates name, type, and value There can be multiple records for the same name and type. DNS servers host the database typically every zone has one or more zone DNS servers

9 DNS Queries DNS Records DNS Components DNS servers can be queried by specifying a name and type For example, name disney.cse.msstate.edu, type A (A is for address) The response is a value corresponding to the name and type Possibly multiple values if multiple records exist for the same name and type. Query: name=cse.msstate.edu, type=a Response: name=cse.msstate.edu, type=a, value=

10 DNS Lookup DNS Records DNS Components Every zone provides it s parent information regarding how to reach the zone server. cse.msstate.edu provides information regarding name servers for cse.msstate.edu to parent zone msstate.edu Consequently root zone knows how to reach it s child edu edu knows how to reach it s child zone msstate.edu msstate.edu knows it s child zone cse.msstate.edu, etc.

11 Recursive and Iterative Queries DNS Records DNS Components Queries could be recursive or non-recursive Query by Q for name disney.cse.msstate.edu, type A Recursive: Q root edu msstate.edu cse.msstate.edu msstate.edu edu root Q Iterative: Q root ; Root Q response is direction to reach edu) Q edu direction to reach msstate.edu) Q msstate.edu direction to reach cse.msstate.edu Q cse.msstate.edu final (authoritative) answer to query Pros and Cons?

12 DNS Resource Record DNS Records DNS Components Each resource record is a five-tuple Domain Name TTL - how stable the record is Class - For Internet, it is IN Type - Many types (next slide) Value - Value corresponding to the type

13 Type Field in Resource Records DNS Records DNS Components SOA (start of authority) - details regarding primary source of info, contact addresses, serial number, flags and time-outs A (Address) - 32 bit IP address - there could be more that one A record (multiple IPs) MX (Mail Exchange) - Mail server for this domain NS (Name Server) CNAME - aliases (eg disney.cse.msstate.edu IN CNAME disney.cs.msstate.edu) PTR - allows for reverse-lookup HINFO - additional info about the machine TXT - Whatever else you want to add!

14 Sample DNS Database Entry DNS Records DNS Components

15 DNS Components DNS Records DNS Components Domain Registrars: sell domain names Zone authority/owner: Creates DNS records pertaining to a zone all records entered in a zone master file Authoritative DNS servers (zone servers): Servers run by the authority. Serves DNS records from the zone master file(s) Root name servers are authoritative for root domain. A gtld name server is authoritative for the gtld. Local DNS servers: typically operated by ISPs (performs iterative queries, caches responses) Stub resolvers: in every host (queries the local DNS server) dig (DNS query tool. Download, install and play with it).

16 Authoritative Name Servers DNS Records DNS Components root servers: A.ROOT-SERVERS.NET, B.ROOT-SERVERS.NET, M.ROOT-SERVERS.NET edu name servers: a.gtld-servers.net., c.gtld-servers.net,... msstate.edu: ns1.msstate.edu, trantor.umd.edu, ns2.msstate.edu. cnn.com: twdns-01.ns.aol.com, twdns-02.ns.aol.com,...

17 DNS Query and Response DNS Records DNS Components Application (for example, browser) requires IP address of groklaw.net Application makes a call to a stub resolver: gethostbyname(groklaw.net) Stub resolver checks in its cache. If A-type record for groklaw.net is found, gethostbyname() returns with the record Else sends query to a local DNS server (LDNS) If LDNS has the answer in it s cache it responds to stub resolver s query.

18 DNS Query and Response DNS Records DNS Components If not found in cache, LDNS maskes iterative queries LDNS sends a query groklaw.net A to a root server Root server sends a response with info regarding ANSs for net LDNS sends the query groklaw.net A to a net name server, and receives info regarding ANSs for groklaw.net LDNS sends a query groklaw.net A to the ANS and receives the desired response. LDNS (caches answer and) sends the response to the stub resolver, gethostbyname(groklaw.net) returns (recall hostent structure returned by gethostbyname())

19 DNS Query/Response Format DNS Records DNS Components Both query and response have the same format Five sections: HEADER QUESTION ANSWER AUTHORITY ADDITION

20 dig DNS Records DNS Components Windows: dig NS (query for root name servers) dig edu NS dig msstate.edu A dig msstate.edu NS

21 dig groklaw.net DNS Records DNS Components QUESTION SECTION: groklaw.net IN A ANSWER SECTION: groklaw.net IN A AUTHORITY: groklaw.net IN NS ns.unc.edu. groklaw.net IN NS ns2.unc.edu. ADDITION: ns.unc.edu IN A ns2.unc.edu IN A

22 Message Transfer Fetching s

23 Basic Components Message Transfer Fetching s Mail clients and servers Two types of clients and servers (sending and receiving) SMTP (simple mail transfer protocol) servers for sending mail IMAP/POP3 servers for making received mails accessible to clients SMTP servers accept s from sending clients Receiving clients fetch from IMAP/POP3 servers Web based services are also popular. RFC 822 specifies formats (for sending to SMTP servers)

24 RFC 822 Header Message Transfer Fetching s

25 RFC 822 Header - Other Fields Message Transfer Fetching s

26 MIME Extensions Message Transfer Fetching s Only printable characters are permitted in RFC 822 format. MIME - for Content description and encoding Content transfer encoding usually base-64 encoding.

27 Message Transfer Fetching s RFC 822 Header MIME Extensions

28 MIME Types Message Transfer Fetching s

29 Message Transfer Fetching s SMTP - Simple Message Transfer Protocol TCP, port 25 Supported commands HELP HELO MAIL FROM RCPT TO DATA

30 SMTP Restrictions Message Transfer Fetching s Max Message length - 64 KB Recursive mailing lists ESMTP (Extended SMTP) New command EHLO - if not accepted, defaults to SMTP.

31 Sending an Message Transfer Fetching s To send an to What is the mail server for somewhere.com? Make a DNS query for (somewhere.com, MX ) e.g., somewhere.com, 82345, IN, MX, mail.something.net Make DNS query for (mail.something.net, A) to determine IP address of mail server e.g. response, mail.something.net,3245, IN, A, Connect to SMTP server (port 25) at IP address use RCPT TO: xyz to check if xyz is a valid address in the domain somewhere.com send in RFC 822 format.

32 Fetching s Message Transfer Fetching s POP3 IMAP Webmail

33 Mail Transfer Modes Message Transfer Fetching s SMTP Internet Message transfer agent User agent (a) Sending host Permanent connection Mailbox Receiving host SMTP Internet Message transfer agent POP3 server POP3 User agent (b) Sending host Mailbox ISP's machine Dial-up connection User's PC

34 POP3 / IMAP Message Transfer Fetching s POP - Post Office Protocol - RFC 1939 POP3 commands - USER, PASS, LIST, RETR, DELE, QUIT IMAP - Internet Message Access Protocol - RFC 2060 Complex, partial message downloads MS Exchange server, GroupWise, Simbra

35

36 A Good Tutorial HTTP Made Really Easy

37 GET To fetch a page from cse.msstate.edu perform DNS query to determine IP address. Connect to port 80 and send a HTTP query. GET / HTTP/1.1\r\n Host: cse.msstate.edu\r\n User-Agent: Mozilla/5.0 Accept: Accept-Language: Accept-Charset: Keep-Alive: 300\r\n Connection: keep-alive\r\n \r\n First two lines are mandatory in every request. Why is second line (Host:) mandatory? Multiple websites may be hosted in a single machine (same IP and port).

38 Header in HTTP Response HTTP/ OK Date: Server:Apache X-Powered-By:PHP / OpenSSL Keep-Alive:timeout=15 Connection: Keep-Alive Transfer-Encoding: Content-Type: \r\n

39 HTTP Status codes

40 HTTP Request Methods

41 HTTP Headers

42 URLs - Uniform Resource Locators

43 Static vs Dynamic HTML Scripting Languages Server-side scripting - CGI, perl, PHP, Python Client-side scripting - Javascript Other client side approaches - Applets, ActiveX

CS3250 Distributed Systems

CS3250 Distributed Systems CS3250 Distributed Systems Lecture 4 More on Network Addresses Domain Name System DNS Human beings (apart from network administrators and hackers) rarely use IP addresses even in their human-readable dotted

More information

Computer Networks 1 (Mạng Máy Tính 1) Lectured by: Dr. Phạm Trần Vũ MEng. Nguyễn CaoĐạt

Computer Networks 1 (Mạng Máy Tính 1) Lectured by: Dr. Phạm Trần Vũ MEng. Nguyễn CaoĐạt Computer Networks 1 (Mạng Máy Tính 1) Lectured by: Dr. Phạm Trần Vũ MEng. Nguyễn CaoĐạt 1 Lecture 10: Application Layer 2 Application Layer Where our applications are running Using services provided by

More information

The Application Layer. CS158a Chris Pollett May 9, 2007.

The Application Layer. CS158a Chris Pollett May 9, 2007. The Application Layer CS158a Chris Pollett May 9, 2007. Outline DNS E-mail More on HTTP The Domain Name System (DNS) To refer to a process on the internet we need to give an IP address and a port. These

More information

Distributed Systems. 09. Naming. Paul Krzyzanowski. Rutgers University. Fall 2015

Distributed Systems. 09. Naming. Paul Krzyzanowski. Rutgers University. Fall 2015 Distributed Systems 09. Naming Paul Krzyzanowski Rutgers University Fall 2015 October 7, 2015 2014-2015 Paul Krzyzanowski 1 Naming things Naming: map names to objects Helps with using, sharing, and communicating

More information

Motivation. Domain Name System (DNS) Flat Namespace. Hierarchical Namespace

Motivation. Domain Name System (DNS) Flat Namespace. Hierarchical Namespace Motivation Domain Name System (DNS) IP addresses hard to remember Meaningful names easier to use Assign names to IP addresses Name resolution map names to IP addresses when needed Namespace set of all

More information

Domain Name System. Overview. Domain Name System. Domain Name System

Domain Name System. Overview. Domain Name System. Domain Name System Overview Domain Name System We look first at how the Domain Name System (DNS) is implemented and the role it plays in the Internet We examine some potential DNS vulnerabilities and in particular we consider

More information

Distributed Systems. 22. Naming. 2013 Paul Krzyzanowski. Rutgers University. Fall 2013

Distributed Systems. 22. Naming. 2013 Paul Krzyzanowski. Rutgers University. Fall 2013 Distributed Systems 22. Naming Paul Krzyzanowski Rutgers University Fall 2013 November 21, 2013 2013 Paul Krzyzanowski 1 My 15 MacBook Pro The rightmost computer on my desk Paul s aluminum laptop, but

More information

Lecture 2 CS 3311. An example of a middleware service: DNS Domain Name System

Lecture 2 CS 3311. An example of a middleware service: DNS Domain Name System Lecture 2 CS 3311 An example of a middleware service: DNS Domain Name System The problem Networked computers have names and IP addresses. Applications use names; IP uses for routing purposes IP addresses.

More information

1 Introduction: Network Applications

1 Introduction: Network Applications 1 Introduction: Network Applications Some Network Apps E-mail Web Instant messaging Remote login P2P file sharing Multi-user network games Streaming stored video clips Internet telephone Real-time video

More information

The Application Layer: DNS

The Application Layer: DNS Recap SMTP and email The Application Layer: DNS Smith College, CSC 9 Sept 9, 0 q SMTP process (with handshaking) and message format q Role of user agent access protocols q Port Numbers (can google this)

More information

Domain Name System (DNS)

Domain Name System (DNS) Application Layer Domain Name System Domain Name System (DNS) Problem Want to go to www.google.com, but don t know the IP address Solution DNS queries Name Servers to get correct IP address Essentially

More information

Glossary of Technical Terms Related to IPv6

Glossary of Technical Terms Related to IPv6 AAAA Record An AAAA record stores a 128-bit Internet Protocol version 6 (IPv6) address, which does not fit the standard A record format. For example, 2007:0db6:85a3:0000:0000:6a2e:0371:7234 is a valid

More information

Domain Name System (DNS)

Domain Name System (DNS) Domain Name System (DNS) Instructor: Anirban Mahanti Office: ICT 745 Email: mahanti@cpsc.ucalgary.ca Class Location: ICT 121 Lectures: MWF 12:00 12:50 Notes derived from Computer Networking: A Top Down

More information

DATA COMMUNICATOIN NETWORKING

DATA COMMUNICATOIN NETWORKING DATA COMMUNICATOIN NETWORKING Instructor: Ouldooz Baghban Karimi Course Book: Computer Networking, A Top-Down Approach By: Kurose, Ross Introduction Course Overview Basics of Computer Networks Internet

More information

NET0183 Networks and Communications

NET0183 Networks and Communications NET0183 Networks and Communications Lecture 25 DNS Domain Name System 8/25/2009 1 NET0183 Networks and Communications by Dr Andy Brooks DNS is a distributed database implemented in a hierarchy of many

More information

Domain Name System. CS 571 Fall 2006. 2006, Kenneth L. Calvert University of Kentucky, USA All rights reserved

Domain Name System. CS 571 Fall 2006. 2006, Kenneth L. Calvert University of Kentucky, USA All rights reserved Domain Name System CS 571 Fall 2006 2006, Kenneth L. Calvert University of Kentucky, USA All rights reserved DNS Specifications Domain Names Concepts and Facilities RFC 1034, November 1987 Introduction

More information

The Domain Name System (DNS)

The Domain Name System (DNS) The Domain Name System (DNS) Columbus, OH 43210 Jain@CIS.Ohio-State.Edu http://www.cis.ohio-state.edu/~jain/ 24-1 Overview Naming hierarchy hierarchy Name resolution Other information in name servers 24-2

More information

Hostnames. HOSTS.TXT was a bottleneck. Once there was HOSTS.TXT. CSCE515 Computer Network Programming. Hierarchical Organization of DNS

Hostnames. HOSTS.TXT was a bottleneck. Once there was HOSTS.TXT. CSCE515 Computer Network Programming. Hierarchical Organization of DNS Hostnames CSCE 515: Computer Network Programming ------ Address Conversion Function and DNS RFC 1034, RFC 1035 Wenyuan Xu http://www.cse..edu/~wyxu/ce515f07.html Department of Computer Science and Engineering

More information

Electronic Mail. The protocols used for Internet can be divided into three broad categories. transfer program. application.

Electronic Mail. The protocols used for Internet  can be divided into three broad categories. transfer program. application. Electronic Mail The protocols used for Internet email can be divided into three broad categories transfer program interface application interface application 33 The Simple Mail Transfer Protocol (SMTP)

More information

DNS : Domain Name System

DNS : Domain Name System 1/30 DNS : Domain Name System Surasak Sanguanpong nguan@.ac.th http://www...ac.th/~nguan Last updated: May 24, 1999 Outline 2/30 DNS basic name space name resolution process protocol configurations Why

More information

DNS Domain Name System

DNS Domain Name System Domain Name System DNS Domain Name System The domain name system is usually used to translate a host name into an IP address Domain names comprise a hierarchy so that names are unique, yet easy to remember.

More information

Applications and Services. DNS (Domain Name System)

Applications and Services. DNS (Domain Name System) Applications and Services DNS (Domain Name Service) File Transfer Protocol (FTP) Simple Mail Transfer Protocol (SMTP) Malathi Veeraraghavan Distributed database used to: DNS (Domain Name System) map between

More information

DNS and E-mail Interface User Guide

DNS and E-mail Interface User Guide DNS and E-mail Interface User Guide Document Revision 04 // 2012 www.twcbc.com back back to TOC to TOC Header Text and Info Table of Contents 1. Introduction 3 2. Accessing the Application 4 3. Working

More information

A DNS Tutorial. Copyright

A DNS Tutorial.  Copyright http://ntrg.cs.tcd.ie/undergrad/4ba2/multicast/ Copyright Table of Contents What is a DNS?... 3 Why do we need a DNS?... 3 Why do computers prefer addresses based on numbers?... 3 What is a Domain Name,

More information

Application Protocols in the TCP/IP Reference Model. Application Protocols in the TCP/IP Reference Model. DNS - Concept. DNS - Domain Name System

Application Protocols in the TCP/IP Reference Model. Application Protocols in the TCP/IP Reference Model. DNS - Concept. DNS - Domain Name System Application Protocols in the TCP/IP Reference Model Application Protocols in the TCP/IP Reference Model File Transfer E-Mail Network Management Protocols of the application layer are common communication

More information

Application Protocols in the TCP/IP Reference Model

Application Protocols in the TCP/IP Reference Model Application Protocols in the TCP/IP Reference Model File Transfer E-Mail Network Management WWW Virtual Terminal Name Service File Transfer HTTP FTP Telnet SMTP DNS SNMP TFTP Internet protocols TCP UDP

More information

Domain Name System (or Service) (DNS) Computer Networks A15

Domain Name System (or Service) (DNS) Computer Networks A15 Domain Name System (or Service) (DNS) Computer Networks A15 DNS Outline Infrastructure Services DNS Hierarchical Structure Root Name Servers Top-Level Domain Servers Authoritative Name Servers Local Name

More information

Domain Name System (DNS) RFC 1034 RFC 1035 http://www.ietf.org

Domain Name System (DNS) RFC 1034 RFC 1035 http://www.ietf.org Domain Name System (DNS) RFC 1034 RFC 1035 http://www.ietf.org TCP/IP Protocol Suite Application Layer DHCP DNS SNMP HTTP SMTP POP Transport Layer UDP TCP ICMP IGMP Network Layer IP Link Layer ARP ARP

More information

Chapter 9: Name Services. 9.1 Introduction 9.2 Name services and the DNS 9.3 Directory services 9.6 Summary

Chapter 9: Name Services. 9.1 Introduction 9.2 Name services and the DNS 9.3 Directory services 9.6 Summary Chapter 9: Name Services 9.1 Introduction 9.2 Name services and the DNS 9.3 Directory services 9.6 Summary Learning objectives To understand the need for naming systems in distributed systems To be familiar

More information

Domain Name System Richard T. B. Ma

Domain Name System Richard T. B. Ma Domain Name System Richard T. B. Ma School of Computing National University of Singapore CS 3103: Compute Networks and Protocols Names Vs. Addresses Names are easier for human to remember www.comp.nus.edu.sg

More information

Domain Name System DNS

Domain Name System DNS CE443 Computer Networks Domain Name System DNS Behnam Momeni Computer Engineering Department Sharif University of Technology Acknowledgments: Lecture slides are from Computer networks course thought by

More information

DNS. Computer Networks. Seminar 12

DNS. Computer Networks. Seminar 12 DNS Computer Networks Seminar 12 DNS Introduction (Domain Name System) Naming system used in Internet Translate domain names to IP addresses and back Communication works on UDP (port 53), large requests/responses

More information

Networking Domain Name System

Networking Domain Name System System i Networking Domain Name System Version 5 Release 4 System i Networking Domain Name System Version 5 Release 4 Note Before using this information and the product it supports, read the information

More information

Applications & Application-Layer Protocols: The Domain Name System and Peerto-Peer

Applications & Application-Layer Protocols: The Domain Name System and Peerto-Peer CPSC 360 Network Programming Applications & Application-Layer Protocols: The Domain Name System and Peerto-Peer Systems Michele Weigle Department of Computer Science Clemson University mweigle@cs.clemson.edu

More information

L4 Domain Name System (DNS)

L4 Domain Name System (DNS) L4 Domain Name System (DNS) by T.S.R.K. Prasad EA C451 Internetworking Technologies 19/01/2013 References / Acknowledgements Sec 2.5: DNS, [Kurose] Sec 9.3.1: Name Service (DNS), [Peterson] Sec 12.3: DNS,

More information

The Domain Name System

The Domain Name System DNS " This is the means by which we can convert names like news.bbc.co.uk into IP addresses like 212.59.226.30 " Purely for the benefit of human users: we can remember numbers (e.g., telephone numbers),

More information

Domain Name System (DNS) Reading: Section in Chapter 9

Domain Name System (DNS) Reading: Section in Chapter 9 Domain Name System (DNS) Reading: Section in Chapter 9 RFC 1034, STD 13 Name Syntax and rules for delegating authority over names Specify implementation of a distributed system that maps names to addresses

More information

Domain Name System (DNS) Fundamentals

Domain Name System (DNS) Fundamentals Domain Name System (DNS) Fundamentals Mike Jager Network Startup Resource Center mike.jager@synack.co.nz These materials are licensed under the Creative Commons Attribution-NonCommercial 4.0 International

More information

Computer Networks. Instructor: Niklas Carlsson Email: niklas.carlsson@liu.se

Computer Networks. Instructor: Niklas Carlsson Email: niklas.carlsson@liu.se Computer Networks Instructor: Niklas Carlsson Email: niklas.carlsson@liu.se Notes derived from Computer Networking: A Top Down Approach, by Jim Kurose and Keith Ross, Addison-Wesley. The slides are adapted

More information

DNS - Domain Name System

DNS - Domain Name System DNS - Domain Name System TCP/IP class 1 outline introduction naming scheme protocol format record types how it works reverse lookup implementation - named config files summary - futures 2 bibliography

More information

Application Protocols in the TCP/IP Reference Model. Application Protocols in the TCP/IP Reference Model. DNS - Domain Name System

Application Protocols in the TCP/IP Reference Model. Application Protocols in the TCP/IP Reference Model. DNS - Domain Name System Application Protocols in the TCP/IP Reference Model Application Protocols in the TCP/IP Reference Model File Transfer E-Mail Network Management Protocols of the application layer are common communication

More information

Basic DNS Course. Module 1. DNS Theory. Ron Aitchison ZYTRAX, Inc. Page 1 of 24

Basic DNS Course. Module 1. DNS Theory. Ron Aitchison ZYTRAX, Inc. Page 1 of 24 Basic DNS Course Module 1 Ron Aitchison ZYTRAX, Inc. Page 1 of 24 The following are the slides used in this Module of the course. Some but not all slides have additional notes that you may find useful.

More information

CS5008: Internet Computing

CS5008: Internet Computing CS5008: Internet Computing Lecture 12: Domains and DNS A. O Riordan, 2009, latest revision 2016 Some slides based on Fitzgerald and Dennis textbook Domains Purpose of Domains: Domains are administrative

More information

internet technologies and standards

internet technologies and standards Institute of Telecommunications Warsaw University of Technology 2015 internet technologies and standards Piotr Gajowniczek Andrzej Bąk Michał Jarociński Internet application layer the email service The

More information

Networking Domain Name System

Networking Domain Name System System i Networking Domain Name System Version 6 Release 1 System i Networking Domain Name System Version 6 Release 1 Note Before using this information and the product it supports, read the information

More information

ECE 4321 Computer Networks. Network Programming

ECE 4321 Computer Networks. Network Programming ECE 4321 Computer Networks Network Programming Name Space System.Net Domain Name System (DNS) To resolve computer naming Host database is split up and distributed among multiple systems on the Internet

More information

How to Add Domains and DNS Records

How to Add Domains and DNS Records How to Add Domains and DNS Records Configure the Barracuda NextGen X-Series Firewall to be the authoritative DNS server for your domains or subdomains to take advantage of Split DNS or dead link detection.

More information

DNS Resolving using nslookup

DNS Resolving using nslookup DNS Resolving using nslookup Oliver Hohlfeld & Andre Schröder January 8, 2007 Abstract This report belongs to a talk given at the networking course (Institue Eurecom, France) in January 2007. It is based

More information

Internet Technologies Internet Protocols and Services

Internet Technologies Internet Protocols and Services QAFQAZ UNIVERSITY Computer Engineering Department Internet Technologies Internet Protocols and Services Dr. Abzetdin ADAMOV Chair of Computer Engineering Department aadamov@qu.edu.az http://ce.qu.edu.az/~aadamov

More information

Domain Name System (DNS) Session-1: Fundamentals. Ayitey Bulley abulley@ghana.com

Domain Name System (DNS) Session-1: Fundamentals. Ayitey Bulley abulley@ghana.com Domain Name System (DNS) Session-1: Fundamentals Ayitey Bulley abulley@ghana.com Computers use IP addresses. Why do we need names? Names are easier for people to remember Computers may be moved between

More information

CS43: Computer Networks Email. Kevin Webb Swarthmore College September 24, 2015

CS43: Computer Networks Email. Kevin Webb Swarthmore College September 24, 2015 CS43: Computer Networks Email Kevin Webb Swarthmore College September 24, 2015 Three major components: mail (MUA) mail transfer (MTA) simple mail transfer protocol: SMTP User Agent a.k.a. mail reader composing,

More information

Mail agents. Introduction to Internet Mail. Message format (2) Authenticating senders

Mail agents. Introduction to Internet Mail. Message format (2) Authenticating senders Mail agents Introduction to Internet Mail Philip Hazel University of Cambridge MUA = Mail User Agent Interacts directly with the end user Pine, MH, Elm, mutt, mail, Eudora, Marcel, Mailstrom, Mulberry,

More information

CS 355. Computer Networking. Wei Lu, Ph.D., P.Eng.

CS 355. Computer Networking. Wei Lu, Ph.D., P.Eng. CS 355 Computer Networking Wei Lu, Ph.D., P.Eng. Chapter 2: Application Layer Overview: Principles of network applications? Introduction to Wireshark Web and HTTP FTP Electronic Mail: SMTP, POP3, IMAP

More information

FTP: the file transfer protocol

FTP: the file transfer protocol File Transfer: FTP FTP: the file transfer protocol at host FTP interface FTP client local file system file transfer FTP remote file system transfer file to/from remote host client/ model client: side that

More information

3. The Domain Name Service

3. The Domain Name Service 3. The Domain Name Service n Overview and high level design n Typical operation and the role of caching n Contents of DNS Resource Records n Basic message formats n Configuring/updating Resource Records

More information

DNS Domain Name System

DNS Domain Name System DNS Domain Name System Domain names and IP addresses People prefer to use easy-to-remember names instead of IP addresses Domain names are alphanumeric names for IP addresses e.g., neon.cs.virginia.edu,

More information

Domain Name System Security

Domain Name System Security Domain Name System Security Guevara Noubir Network Security Northeastern University 1 Domain Name System DNS is a fundamental applica=on layer protocol Not visible but invoked every =me a remote site is

More information

Domain Name System (or Service) (DNS) Computer Networks Term B10

Domain Name System (or Service) (DNS) Computer Networks Term B10 Domain Name System (or Service) (DNS) Computer Networks Term B10 DNS Outline DNS Hierarchial Structure Root Name Servers Top-Level Domain Servers Authoritative Name Servers Local Name Server Caching and

More information

DNS Basics. DNS Basics

DNS Basics. DNS Basics DNS Basics 1 A quick introduction to the Domain Name System (DNS). Shows the basic purpose of DNS, hierarchy of domain names, and an example of how the DNS protocol is used. There are many details of DNS

More information

How do I get to www.randomsite.com?

How do I get to www.randomsite.com? Networking Primer* *caveat: this is just a brief and incomplete introduction to networking to help students without a networking background learn Network Security. How do I get to www.randomsite.com? Local

More information

Application Layer: DNS

Application Layer: DNS Application Layer: DNS Prof. Andrzej Duda duda@imag.fr http://duda.imag.fr 1 Overview Learn about protocols by examining popular application-level protocols DNS - name service 2 Applications and application-layer

More information

Fig 1A portion of the Internet domain name space.

Fig 1A portion of the Internet domain name space. 1 Asst. Lecturar ahmed S. Kareem DNS The Domain Name System Although programs theoretically could refer to hosts, mailboxes, and other resources by their network (e.g., IP) addresses, these addresses are

More information

Outline. Definition. Name spaces Name resolution Example: The Domain Name System Example: X.500, LDAP. Names, Identifiers and Addresses

Outline. Definition. Name spaces Name resolution Example: The Domain Name System Example: X.500, LDAP. Names, Identifiers and Addresses Outline Definition Names, Identifiers and Addresses Name spaces Name resolution Example: The Domain Name System Example: X.500, LDAP CS550: Advanced Operating Systems 2 A name in a distributed system is

More information

Names vs. Addresses. Flat vs. Hierarchical Space. Domain Name System (DNS) Computer Networks. Lecture 5: Domain Name System

Names vs. Addresses. Flat vs. Hierarchical Space. Domain Name System (DNS) Computer Networks. Lecture 5: Domain Name System Names vs. Addresses Computer Networks Lecture 5: Domain Name System Names are easier for human to remember www.umich.edu vs. 141.213.4.4 Addresses can be changed without changing names move www.umich.edu

More information

Internet-Praktikum I Lab 3: DNS

Internet-Praktikum I Lab 3: DNS Kommunikationsnetze Internet-Praktikum I Lab 3: DNS Mark Schmidt, Andreas Stockmayer Sommersemester 2015 kn.inf.uni-tuebingen.de Motivation for the DNS Problem IP addresses hard to remember for humans

More information

The Domain Name System (DNS)

The Domain Name System (DNS) The Domain Name System (DNS) Each Internet host is assigned a host name and an IP address Host names are structured character strings, e.g., www.cs.iastate.edu IP addresses are 32 bit integers, e.g., 129.186.3.6

More information

How to set up the Integrated DNS Server for Inbound Load Balancing

How to set up the Integrated DNS Server for Inbound Load Balancing How to set up the Integrated DNS Server for Introduction Getting Started Peplink Balance has a built-in DNS server for inbound link load balancing. You can delegate a domain s NS/SOA records, e.g. www.mycompany.com,

More information

Networking Domain Name System

Networking Domain Name System IBM i Networking Domain Name System Version 7.2 IBM i Networking Domain Name System Version 7.2 Note Before using this information and the product it supports, read the information in Notices on page

More information

Internet Security [1] VU 184.216. Engin Kirda engin@infosys.tuwien.ac.at

Internet Security [1] VU 184.216. Engin Kirda engin@infosys.tuwien.ac.at Internet Security [1] VU 184.216 Engin Kirda engin@infosys.tuwien.ac.at Christopher Kruegel chris@auto.tuwien.ac.at Administration Challenge 2 deadline is tomorrow 177 correct solutions Challenge 4 will

More information

Application layer Web 2.0

Application layer Web 2.0 Information Network I Application layer Web 2.0 Youki Kadobayashi NAIST They re revolving around the web, after all Name any Internet-related buzz: Cloud computing Smartphone Social media... You ll end

More information

INTERNET DOMAIN NAME SYSTEM

INTERNET DOMAIN NAME SYSTEM INTERNET DOMAIN NAME SYSTEM http://www.tutorialspoint.com/internet_technologies/internet_domain_name_system.htm Copyright tutorialspoint.com Overview When DNS was not into existence, one had to download

More information

loss-tolerant and time sensitive loss-intolerant and time sensitive loss-intolerant and time insensitive

loss-tolerant and time sensitive loss-intolerant and time sensitive loss-intolerant and time insensitive CS326e Quiz 5 The first correct 10 answers will be worth 1 point each. Each subsequent correct answer will be worth 0.2 points. Circle the correct answer. UTEID The transfer of an html file from one host

More information

Evolution of the WWW. Communication in the WWW. WWW, HTML, URL and HTTP. HTTP Abstract Message Format. The Client/Server model is used:

Evolution of the WWW. Communication in the WWW. WWW, HTML, URL and HTTP. HTTP Abstract Message Format. The Client/Server model is used: Evolution of the WWW Communication in the WWW World Wide Web (WWW) Access to linked documents, which are distributed over several computers in the History of the WWW Origin 1989 in the nuclear research

More information

CS3600 SYSTEMS AND NETWORKS

CS3600 SYSTEMS AND NETWORKS CS3600 SYSTEMS AND NETWORKS FALL 2011 Lecture 19: DNS Prof. Alan Mislove (amislove@ccs.neu.edu) Slides used with permissions from Edward W. Knightly, T. S. Eugene Ng, Ion Stoica, Hui Zhang Human Involvement

More information

Application-layer protocols

Application-layer protocols Application layer Goals: Conceptual aspects of network application protocols Client server paradigm Service models Learn about protocols by examining popular application-level protocols HTTP DNS Application-layer

More information

DNS: Domain Name System

DNS: Domain Name System DNS: Domain Name System People: many identifiers: SSN, name, passport # Internet hosts, routers: IP address (32 bit) - used for addressing datagrams name, e.g., ww.yahoo.com - used by humans Q: map between

More information

- Domain Name System -

- Domain Name System - 1 Name Resolution - Domain Name System - Name resolution systems provide the translation between alphanumeric names and numerical addresses, alleviating the need for users and administrators to memorize

More information

Cours du 22 novembre

Cours du 22 novembre Cours du 22 novembre Couche application DNS Application Layer 2-2 DNS: domain name system people: many identifiers: SSN, name, passport # Internet hosts, routers: IP address (32 bit) - used for addressing

More information

CS 348: Computer Networks. - DNS; 22 nd Oct 2012. Instructor: Sridhar Iyer IIT Bombay

CS 348: Computer Networks. - DNS; 22 nd Oct 2012. Instructor: Sridhar Iyer IIT Bombay CS 348: Computer Networks - DNS; 22 nd Oct 2012 Instructor: Sridhar Iyer IIT Bombay Domain Name System Map between host names and IP addresses People: many identifiers: name, Passport #, Internet hosts:

More information

Homework 2 assignment for ECE374 Posted: 02/20/15 Due: 02/27/15

Homework 2 assignment for ECE374 Posted: 02/20/15 Due: 02/27/15 1 Homework 2 assignment for ECE374 Posted: 02/20/15 Due: 02/27/15 ote: In all written assignments, please show as much of your work as you can. Even if you get a wrong answer, you can get partial credit

More information

Computer Networks Prof. S. Ghosh Department of Computer Science and Engineering Indian Institute of Technology, Kharagpur Lecture - 34 DNS & Directory

Computer Networks Prof. S. Ghosh Department of Computer Science and Engineering Indian Institute of Technology, Kharagpur Lecture - 34 DNS & Directory Computer Networks Prof. S. Ghosh Department of Computer Science and Engineering Indian Institute of Technology, Kharagpur Lecture - 34 DNS & Directory Good day. Today we will take up two topics, DNS and

More information

Copyright International Business Machines Corporation 2001. All rights reserved. US Government Users Restricted Rights Use, duplication or disclosure

Copyright International Business Machines Corporation 2001. All rights reserved. US Government Users Restricted Rights Use, duplication or disclosure iseries DNS iseries DNS Copyright International Business Machines Corporation 2001. All rights reserved. US Government Users Restricted Rights Use, duplication or disclosure restricted by GSA ADP Schedule

More information

Application layer Protocols application transport

Application layer Protocols application transport Application layer Protocols application transport data link physical Network Applications and Application Layer Protocols Network applications: running in end systems (hosts) distributed, communicating

More information

DNS. Computer networks - Administration 1DV202. fredag 30 mars 12

DNS. Computer networks - Administration 1DV202. fredag 30 mars 12 DNS Computer networks - Administration 1DV202 DNS History Who needs DNS? The DNS namespace How DNS works The DNS database The BIND software Server and client configuration The history of DNS RFC 882 and

More information

Security Analysis of DNS & Applications/Email

Security Analysis of DNS & Applications/Email Security Analysis of DNS & Applications/Email EE 122: Intro to Communication Networks Fall 2007 (WF 4-5:30 in Cory 277) Vern Paxson TAs: Lisa Fowler, Daniel Killebrew & Jorge Ortiz http://inst.eecs.berkeley.edu/~ee122/

More information

Naming. Name Service. Why Name Services? Mappings. and related concepts

Naming. Name Service. Why Name Services? Mappings. and related concepts Service Processes and Threads: execution of applications or services Communication: information exchange for coordination of processes But: how can client processes (or human users) find the right server

More information

THE DOMAIN NAME SYSTEM DNS

THE DOMAIN NAME SYSTEM DNS Announcements THE DOMAIN NAME SYSTEM DNS Internet Protocols CSC / ECE 573 Fall, 2005 N. C. State University copyright 2005 Douglas S. Reeves 2 Today s Lecture I. Names vs. Addresses II. III. IV. The Namespace

More information

DNS. The Root Name Servers. DNS Hierarchy. Computer System Security and Management SMD139. Root name server. .se name server. .

DNS. The Root Name Servers. DNS Hierarchy. Computer System Security and Management SMD139. Root name server. .se name server. . Computer System Security and Management SMD139 Lecture 5: Domain Name System Peter A. Jonsson DNS Translation of Hostnames to IP addresses Hierarchical distributed database DNS Hierarchy The Root Name

More information

Introduction. Friday, June 21, 2002

Introduction. Friday, June 21, 2002 This article is intended to give you a general understanding how ArGoSoft Mail Server Pro, and en Email, in general, works. It does not give you step-by-step instructions; it does not walk you through

More information

Connecting with Computer Science, 2e. Chapter 5 The Internet

Connecting with Computer Science, 2e. Chapter 5 The Internet Connecting with Computer Science, 2e Chapter 5 The Internet Objectives In this chapter you will: Learn what the Internet really is Become familiar with the architecture of the Internet Become familiar

More information

Naming and the DNS. Focus. How do we name hosts etc.? Application Presentation Topics. Session Domain Name System (DNS) Email/URLs

Naming and the DNS. Focus. How do we name hosts etc.? Application Presentation Topics. Session Domain Name System (DNS) Email/URLs Naming and the DNS Focus How do we name hosts etc.? Application Presentation Topics Session Domain Name System (DNS) Email/URLs Transport Network Data Link Physical Ldns.1 Names and Addresses 43 name address

More information

CSE 265: System & Network Administration

CSE 265: System & Network Administration CSE 265: System & Network Administration DNS The Domain Name System History of DNS What does DNS do? The DNS namespace BIND software How DNS works DNS database Testing and debugging (tools) DNS History

More information

Motivation. Users can t remember IP addresses. Implemented by library functions & servers. - Need to map symbolic names (www.stanford.

Motivation. Users can t remember IP addresses. Implemented by library functions & servers. - Need to map symbolic names (www.stanford. Motivation 2 cs.princeton.edu User 1 user @ cs.princeton.edu Name server Mail program 192.12.69.5 3 TCP 192.12.69.5 4 192.12.69.5 5 IP Users can t remember IP addresses - Need to map symbolic names (www.stanford.edu)

More information

Agenda. Network Services. Domain Names. Domain Name. Domain Names Domain Name System Internationalized Domain Names. Domain Names & DNS

Agenda. Network Services. Domain Names. Domain Name. Domain Names Domain Name System Internationalized Domain Names. Domain Names & DNS Agenda Network Services Domain Names & DNS Domain Names Domain Name System Internationalized Domain Names Johann Oberleitner SS 2006 Domain Names Naming of Resources Problems of Internet's IP focus IP

More information

Installing and Setting up Microsoft DNS Server

Installing and Setting up Microsoft DNS Server Training Installing and Setting up Microsoft DNS Server Introduction Versions Used Windows Server 2003 Setup Used i. Server Name = martini ii. Credentials: User = Administrator, Password = password iii.

More information

CS 640 Introduction to Computer Networks. Today s lecture. Lecture18. Domain Name System Overview

CS 640 Introduction to Computer Networks. Today s lecture. Lecture18. Domain Name System Overview Introduction to Computer Networks Lecture18 Today s lecture Domain Name System Overview The hierarchy of domain s DNS records The resolution process Domain Name System Overview What are s used for in general?

More information

Computer Networks: Domain Name Service (DNS)

Computer Networks: Domain Name Service (DNS) Computer Networks: Domain Name Service (DNS) CS 3516 D- term 2013 Instructor: Krishna Venkatasubramanian Quiz 2 DNS: domain name system people: many identifiers: SSN, name, passport # Internet hosts, routers:

More information

Computer Networks - CS132/EECS148 - Spring 2013 ------------------------------------------------------------------------------

Computer Networks - CS132/EECS148 - Spring 2013 ------------------------------------------------------------------------------ Computer Networks - CS132/EECS148 - Spring 2013 Instructor: Karim El Defrawy Assignment 2 Deadline : April 25 th 9:30pm (hard and soft copies required) ------------------------------------------------------------------------------

More information

Chapter 23 The Domain Name System (DNS)

Chapter 23 The Domain Name System (DNS) CSC521 Communication Protocols 網 路 通 訊 協 定 Chapter 23 The Domain Name System (DNS) 吳 俊 興 國 立 高 雄 大 學 資 訊 工 程 學 系 Outline 1. Introduction 2. Names For Machines 3. Flat Namespace 4. Hierarchical Names 5.

More information

Domain Name System. Heng Sovannarith heng_sovannarith@yahoo.com

Domain Name System. Heng Sovannarith heng_sovannarith@yahoo.com Domain Name System Heng Sovannarith heng_sovannarith@yahoo.com Introduc:on to DNS Domain Name System is a distributed database system that can be serve as the founda:on for name resolu:on in a TCP/IP Network.

More information