Система доменных имён (DNS)

1. DNS

2. DNS namespace

3. fully qualified domain name (FQDN)

Hostname
Domain
Top level
AcctDirPC
adatum
com
Fully qualified domain name = AcctDirPC.adatum.com

4.

DNS zone – часть от DNS пространства имен,
которая содержит DNS записи
Типы DNS Zone :
• Forward lookup zone
• Reverse lookup zone
fqdn -> ip
ip
-> fqdn
Ресурсные записи forward lookup zones:
• A, - fqdn=ipv4
• AAAA – fqdn=ipv6
• CNAME, MX, SRV, NS, SOA
Ресурсные записи в reverse lookup zones:
• PTR – ipv4=fqdn

5. DNS Names Resolving в Internet

.root DNS
Какой IP address у
www.microsoft.com?
2
3
1
Workstation
.com DNS
Local DNS Server
4
207.46.230.219 у
www.microsoft.com
5
Microsoft.com DNS

6. Что используется и в какой последовательности используется для Resolving

LMHosts File
8
Broadcast
1
7
Local Host
Name
2
6
DNS Resolver
Cache/Hosts file
content
3
WINS Server
5
NetBIOS Name
Cache
4
LLMNR
DNS Server

7. DNS recurcive query, DNS iterative query

recursive запрос отправился к DNS server
и он отправил ответ на запрос
mail1.contoso.com
172.16.64.11
DNS client
Local DNS server

8. DNS query

Client
Recursive query
mail1.contoso.com
172.16.64.11
Iterative query
Ask .com
Iterative query
Ask contoso.com
Local
DNS server
Root hint (.)
Iterative query
Authoritative response
.com
contoso.com

9. Root Hints

Root hints содержит IP адреса for
DNS root серверов
Root (.) Servers
DNS Servers
Root
Hints
com
DNS
Server
Client
microsoft

10. Forwarder

A forwarder is a DNS server назначенный для отправки
resolving запросов external or offsite DNS domain
names
Client
Recursive query
mail1.contoso.com
131.107.0.11
Iterative query
Root hint (.)
Ask .com
Recursive query
Iterative query
Ask contoso.com
131.107.0.11
Local
DNS server
Iterative query
Authoritative response
Forwarder
.com
contoso.com

11. Conditional Forwarder

Conditional forwarding пересылает запросы используя
условия на сервер имени домена
All Other DNS Domains
Query for
www.contoso.com
Local
DNS server
ISP DNS
contoso.com
Client
contoso.com
DNS

12. DNS Server Caching

DNS server cache
Host name
IP address
TTL
ServerA.contoso.com
131.107.0.44
28 seconds
Where isis at
ServerA
ServerA?
131.107.0.44
Client1
ServerA
Where isis at
131.107.0.44
ServerA?
Client2
ServerA

13. Типы DNS Zone

Zones
Description
Primary
Read/write copy of a DNS database
Secondary
Read-only copy of a DNS database
Stub
Copy of a zone that contains only records used
to locate name servers
Active Directoryintegrated
Zone data is stored in AD DS rather than in
zone files