The Domain Name System (DNS) is a hierarchical decentralized naming system that resolves Name to IP or vise versa. DNS works with port no 53 (TCP and UDP ) For query resolving UDP protocol is used and for Zone transfer TCP port is used.

1. DOMAIN NAMING SYSTEM
Submitted by :
Chinmoy jena

2. DNS
 The Domain Name System (DNS) is a hierarchical decentralized naming
system that resolves Name to IP or vise versa.
 DNS works with port no 53 (TCP and UDP )
 For query resolving UDP protocol is used and for Zone transfer TCP port is
used.
mail.google.com
Third level domain
Second level domain
TOP level Domain

3. HOW DNS WORKS?

4. ZONE
There are 2 type of zone:
 Forward lookup zone
Maps Hostname to IP address
 Reverse Lookup Zone
Maps IP address to hostname

5. TYPES OF ZONE
Primary zone
 When a zone that this DNS server hosts is a primary zone and it stores the
master copy of zone data in a local file or in AD DS.
 zone file is named zone_name.dns and located in %windir%System32Dns
folder
Secondary zone
 When a zone that this DNS server hosts is a secondary zone, this DNS server
is a secondary source for information about this zone.
 Secondary zone is merely a copy of a primary zone that is hosted on another
server
Stub zone
 When a zone that this DNS server hosts is a stub zone, this DNS server is a
source only for information about the authoritative name servers for this zone.
The zone at this server must be obtained from another DNS server that hosts
the zone.
 Contains information only about the authoritative name servers for the zone.

6. ROOT HINTS
 If the DNS server does not know the address of the requested site, then it will
forward the request to root DNS server.
 The root hints are stored in a file named cache.dns that is located in the
WindowsSystem32Dns folder.
 There are 13 root hint servers around
the world.

7. TYPES OF RECORD
 A -IPv4 address
 AAAA -IPv6 Address
 CNAME -Canonical Name
 PTR -Pointer Record
 NS -Name server
 SOA -State Of Authority
 SRV -Service locator record
 MX -Mail Exchange
 TXT -Text Record

8. BACKUP AND RESTORE DNS
To backup DNS
dnscmd /ZoneExport <zone name> <zone file name>
Recover from Backup
dnscmd /zoneadd “zone name” /primary /file “zone name file” /load

9. TROUBLESHOOTING DNS
1. Nslookup
2. Restart Service
3. Clear DNS Cache