ppt-domain-name-system-04-200100 (1).ppt

he Domain Name System (DNS) is the phonebook of the Internet. Humans access information online through domain names, like nytimes.com or espn.com. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources. ach device connected to the Internet has a unique IP address which other machines use to find the device. DNS servers eliminate the need for humans to memorize IP addresses such as 192.168.1.1 (in IPv4), or more complex newer alphanumeric IP addresses such as 2400:cb00:2048:1::c629:d7a2 (in IPv6). he process of DNS resolution involves converting a hostname (such as www.example.com) into a computer-friendly IP address (such as 192.168.1.1). An IP address is given to each device on the Internet, and that address is necessary to find the appropriate Internet device - like a street address is used to find a particular home. When a user wants to load a webpage, a translation must occur between what a user types into their web browser (example.com) and the machine-friendly address necessary to locate the example.com webpage.

In order to understand the process behind the DNS resolution, it’s important to learn about the different hardware components a DNS query must pass between. For the web browser, the DNS lookup occurs "behind the scenes" and requires no interaction from the user’s computer apart from the initial request. DNS recursor - The recursor can be thought of as a librarian who is asked to go find a particular book somewhere in a library. The DNS recursor is a server designed to receive queries from client machines through applications such as web browsers. Typically the recursor is then responsible for making additional requests in order to satisfy the client’s DNS query.
Root nameserver - The root server is the first step in translating (resolving) human readable host names into IP addresses. It can be thought of like an index in a library that points to different racks of books - typically it serves as a reference to other more specific locations.
TLD nameserver - The top level domain server (TLD) can be thought of as a specific rack of books in a library. This nameserver is the next step in the search for a specific IP address, and it hosts the last portion of a hostname (In example.com, the TLD server is “com”).
Authoritative nameserver - This final nameserver can be thought of as a dictionary on a rack of books, in which a specific name can be translated into its definition. The authoritative nameserver is the last stop in the nameserver query. If the authoritative name server has access to the requested record, it will return the IP address for the requested hostname back to the DNS Recursor (the librarian) that made the initial request. Both concepts refer to servers (groups of servers) that are integral to the DNS infrastructure, but each performs a different role and lives in different locations inside the pipeline of a DNS query. One way to

1. Domain Name System (DNS)
Onno W. Purbo
[email protected]

2. Mengapa DNS?
Manusia “ingat” nama, komputer kenal
angka.
Perkembangan jaringan pesat.
File /etc/hoststidak memadai.
Desentralisasi pemeliharaan jaringan.

3. Prinsip Kerja DNS
DNS Client
query answer
DNS
Server
Resolver
TCP/IP
Application

4. Informasi DNS
IP address
Canonical Name
Mail Exchanger
Informasi Hardware
Sistem Operasi
Hostname

5. Implementasi DNS
DNS server
/etc/named
named.boot
zona file
Resolver
/etc/resolv.conf
Atau
/etc/host.conf

6. Implementasi Host Table
/etc/hosts
/windows/hosts
Format Penulisan
<ip_address> <hostname><cname>
Contoh/etc/hosts
167.205.22.123 maingtw.paume.itb.ac.id.
167.205.22.124www.itb.ac.id.www
127.0.0.1 localhost

7. Kenapa /etc/hosts
Jumlah host sedikit
Jaringan tidak terhubung ke Internet
/etc/hosts digunakan oleh NIS (pada
Sun)
Tidak semua host pakai UNIX

8. Top Level Domain &
Subdomain

9. Known TLD
World
edu : nsf.mit.edu
Com : ibm.com
gov : nasa.gov
mil : navy.mil
net : nsf.net
org : ampr.org
In other countries
jp ; Jepang
nl ; Netherland
au ; Australia
uk ; Inggris
de ; Jerman
th ; Thailand

10. Domain ID
Top Level Domain:id
Beberapa Sub-Domain
ac.id : Lemb. Pendidikan
go.id : Lemb. Pemerintahan
co.id : Lemb. Komersial
or.id : Lemb. Non Profit
net.id : Network Provider
sch.id : Sekolah

11. Konfigurasi DNS Server
File-file yang dibutuhkan
/etc/named (executable file)
boot script (default : /etc/named.boot)
zona file
DNS server run sebagai “daemon” proses

12. Konfigurasi boot script
Directory
Primary
Secondary
Cache
forwarders
Penyimpanan zona file
Server sebagai primary
Server sebagai secondary
Cache only server
Server sebagai forwarder

13. Konfigurasi Cache-only server
Konfigurasi minimal dari DNS server
Setiap query akan diteruskan ke root
server
format
cache . db.cache

14. Primary & Secondary Server
Primary server “memelihara” langsung
zona file
Secondary server sebagai “image” dari
primary server
Proses updating dengan “zona transfer”
DNS server dapat merupakan primary
dan secondary dari beberapa domain

15. Format
Primary <domain> <zona file>
Secondary <domain> <server> <image file>
Contoh
Directory /etc/named.data
Primary itb.ac.id db.itb
Secondary ee.itb.ac.id 167.205.136.132 db.ee
Secondary telkom.go.id 167.205.136.5db.telkom
Secondary bppt.go.id 202.46.1.2 db.bppt

16. Server
bppt.go.id
Server
telkom.go.id
DNS
Server
Server
ee.itb.ac.id
Resolver
answer
query

17. Reserve Domain Server
Memetakan IP address ke hostname
Diperlukan untuk log file dan security
IP address digunakan sebagai domain
Top Level domain in-addr.arpa
Sub-Domain dibentuk dari IP address
mulai dari Most Significant Digit

18. Reverse Domain Tree
arpa
in-addr
1 2
255
167
205
1 2

19. Contoh Reverse Domain
ex : Network dengan IP address klas B
167.205.xx.xx mempunyai reverse
domain
205.167.in-addr.arpa
ex : Network dengan IP address klas C
196.3.6.xx mempunyai reverse domain
6.3.196.in-adr.arpa

20. Deklarasi Reverse Domain
Server pada boot script
Format (sbg primary dan secondary)
primary <rev_domain> zona file
secondary <rev_domain> <server> zona file
Contoh
primary 205.167.in-addr.arpa db.167.205.21
secondary 1.46.202.in -addr.arpa 202.46.1.2 db.202

21. Standard Resource Record
Start of Authority Record (SOA)
Name Server(NS)
Address Record (A)
Mail Exchanger Record (MX)
Canonical Name Record (CNAME)
Host Information Record (HINFO)
Well Known Services Record (WKS)

22. Start of Authority (SOA)
Format
[zone] IN SOA origin contact (
serial
refresh
retry
expire
minimum
)

23. Name Server Record (NS)
Mendeklarasikan DNS server untuk zona
file (Boleh lebih dari satu host)
Format
[domain] IN NS server

24. Address Record (A)
Mendeklarasikan IP address dari host-
host yang terdapat pada zona file
Format
[host] IN A address

25. Mail Exchanger Record (MX)
Mendeklarasikan Mail Server untuk
suatu domain ataupun suatu host
Format
[name] IN MX preference host

26. Canonical Name (CNAME)
Mendeklarasikan alias name untuk
suatu host
Format
nicknameIN CNAME host

27. Host Information (HINFO)
Mendeklarasikan informasi singkat
tentang hardware dan sistem operasi
dari suatu host
Format
[host] IN HONFO hardware software

28. Well Known Services (WKS)
Memberikan informasi tentang layanan
yang disediakan oleh suatu host
Format
[host] IN WKS address protocol services

29. Pointer to Hostname (PTR)
Memberi informasi hostname dari IP
address suatu host
Format
[number_in_Class] IN PTR FQDN

30. Konfigurasi Cache File
Digunakan untuk mengakses root
server
ex:
.99999999IN NS ns.nic.ddn.mil
ns.nic.ddn.mil IN A 192.112.36.4

31. Start DNS Server
Di run bila boot script dan zona file
telah dibuat sebelumnya

32. Run dari Shell
Command
# named -b /etc/named.boot

33. Konfigurasi Resolver
Bagaimana Client akses DNS server?

34. File /etc/resolve.conf
Format
domain<domain_name>
server<IP_addr_DNS_Sercer>
ex: domain itb.ac.id
server 167.205.22.123

35. DNS dan Mail
Bagaimana Electronic Mail
Menggunakan MX Record pada DNS
Server..?
Bagaimana mengirimkan E-mail ke host
yang tidak menjalankan aplikasi Mail
Server

36. Proses Pengiriman Mail
Remote host akan mengirim pertama
kali ke Mail Server dengan preference
terendah (prioritas tertinggi)
Remote host dengan preference paling
tinggi merupakan prioritas terendah
MX record dapat digunakan untuk Wide
Domain Aliases

37. Proses Mail
System INMX40mail.bppt.go.id
IN MX 30 gtw.itb.ac.id
IN Mx 20 system.itb.ac.id
Catatan :
Prioritas tertinggi adalah host itu sendiri

38. Utility nslookup
Untuk mengetahui apakah DNS server
dapat berjalan sebagaiman mestinya ...

39. Menggunakan nslookup
Dari shell prompt
maingtw # nslookup itbgtw.itb.ac.id
Server: maingtw.paume.itb.ac.id
Address: 0.0.0.0
Name: itbgtw.itb.ac.id
Addresses:167.205.22.101,167.205.20.1

40. Menggunakan nslookup
Secara Interaktif
maingtw # nslookup
Server:maingtw.paume.itb.ac.id
Address:0.0.0.0
> ?

41. Pemeliharaan & Updating DNS
Bagaimana perubahan zona file dapat
diupdate oleh secondary server..?

42. Tips
Updating SOA diikuti dengan
menambah serial number
Gunakan beberapa secondary server
untuk kehandalan system
Koordinasi dengan Adminintrator DNS
lainnya.
Updating root server