2013 2014 Data Communication Systems Lab Ders Sorumlusu: Yrd. Doç. Dr. İ. Muharrem ORAK Laboratuvar Sorumluları:Ar.Gör. Bilal KAYA
LABORATUARLAR KURALLARI 1. Laboratuvarlar programda belirtilen giriş ve çıkış saatlerine uygun olarak yapılır. laboratuvara 15 dakika ve daha fazla süre geç kalan öğrenciler alınmaz. 2. Laboratuvara gelmeden önce öğrencilerin o gün yapacakları deneylere ait deney föyünü dikkatle okumaları ve deneyle ilgili teorik bilgileri çeşitli kaynaklardan öğrenmiş olmaları gerekir. 3. Deneyden önce ve deney süresince konu hakkında sorular sorulur, bu sorulara alınan cevaplar ve deney raporları referans alınarak öğrencinin deney notu belirlenir. 4. Her öğrenci kendi deneyini yapmakla sorumludur. Başkalarından sonuçları alan ya da başkalarına sonuçlarını veren öğrencilerin deneyi iptal edilir, deneyi yapmamış kabul edilir.
Konu: DNS Protokolünün Analizi Amaç ve Kapsam 1. DNS prokotolunun çalışma şeklinin öğrenilmesi Teorik Bilgiler Figure 19.1 Purpose of DNS User 1 Host name Host name 2 6 IP address Transport layer 5 IP address 3 Query Response 4 TCP/IP Protocol Suite 5
DNS History (1) ARPANET utilized a central file HOSTS.TXT Contains names to addresses mapping Maintained by SRI s NIC (Stanford-Research- Institute: Network-Information-Center) Administrators email changes to NIC NIC updates HOSTS.TXT periodically Administrators FTP (download) HOSTS.TXT
DNS History (2) As the system grew, HOSTS.TXT had problems with: Scalability (traffic and load) Name collisions Consistency In 1984, Paul Mockapetris released the first version (RFCs 882 and 883, superseded by 1034 and 1035 ) Name Space Structure. (root) edu com org gov us ins company finance hr mfg ins.com Domain company.us Domain Module 6 6
Name Servers and Zones 128.8.10.5 serves data for both nominum.com and isc.org zones 202.12.28.129 serves data for nominum.com zone only 204.152.187.11 serves data for isc.org zone only Name Servers 128.8.10.5 202.12.28.129 204.152.187.11 Zones nominum.com isc.org The Resolution Process Let s look at the resolution process step-bystep:
The Resolution Process The workstation annie asks its configured name server, dakota, for www.nominum.com s address What s the IP address of www.nominum.com? The Resolution Process The name server dakota asks a root name server, m, for www.nominum.com s address What s the IP address of www.nominum.com?
The Resolution Process The root server m refers dakota to the com name servers This type of response is called a referral Here s a list of the com name servers. Ask one of them. The Resolution Process The name server dakota asks a com name server, f, for www.nominum.com s address What s the IP address of www.nominum.com? f.gtld-servers.net
The Resolution Process The com name server f refers dakota to the nominum.com name servers Here s a list of the nominum.com name servers. Ask one of them. f.gtld-servers.net The Resolution Process The name server dakota asks a nominum.com name server, ns1.sanjose, for www.nominum.com s address What s the IP address of www.nominum.com? ns1.sanjose.nominum.net f.gtld-servers.net
The Resolution Process The nominum.com name server ns1.sanjose responds with www.nominum.com s address Here s the IP address for www.nominum.com ns1.sanjose.nominum.net f.gtld-servers.net The Resolution Process The name server dakota responds to annie with www.nominum.com s address Here s the IP address for www.nominum.com ns1.sanjose.nominum.net f.gtld-servers.net
DNS Concepts Resolution Module 6 18 Figure 19.14 Query and response messages TCP/IP Protocol Suite 28