DNS (Domain Naming service):
It resolves hostname to IP address and IP address to hostname (Vice versa).
Zones are categorized in one of 2 categories.
- Forward lookup zone — DNS servers maps FQDNs to IP address
ii.Reverse lookup zone — DNS Servers maps IP address to FQDNs. (FQDN- Fully Qualified Domain name)
- Primary Zone
2. Secondary zone
— It is a backup of Primary Zone. Primary Zone is read and write copy where as secondary zone is read only copy.
- Stub zone
— It used to reduce the network traffic.
— It contains only two records.
- SOA(Start of Authority): It maintains the record of primary zone. i.e., it maintains the information that how many times the primary zone is modified .And also it maintains the replication between primary and secondary zone and between primary and stub zone.
- NS : It Checks the authorized servers present in the network . It also checks which DNS Server is resolving host to IP.
Understanding server types:
- Primary servers
- Standard primary zones
b. Active directory integrated zones
- Secondary servers
- Stub Servers
- Cache-only servers
– A (Host)
– CNAME (Alias)
– MX (Mail Exchange)
– PTR (Pointer)
– SOA (Start of Authority)
– NS (Name Source) .. etc…
Query(Requesting for an address):
Two types of Queries:
- Recursive Query
— If a client request for an address, the dns server reply will back to the client. The reply can be positive reply or it can be a negative reply. If it is a negative reply then the client has to contact other DNS Servers present in the network requesting for that address.
- Iterative Query
— If a client request for an address, if that information is not available in that DNS Server then the DNS Server will sendthe query to other DNS Servers present in the network.
Active Directory Integrated Zone:
— While installing active directory, if DNS Services are installed ,it will create active directory integrated zone with the domain name.
— If the information of that zone will be stored in the databse of AD.
— If a zone integrated with AD then zone name and domain name are same.
— It contains 6 service records.
v. Domain DNS Zone
vi. Forest DNS Zone
— To Configure a seperate DNS Server on the other system then DNS server must be integrated with AD then all 6 service records are transferred to other DNS Server.
How to COnfigure a seperate DNS Server integrated with AD??
— Create a secondary zone with the domain name, transfer that zone from primary.
— If the zone is not loaded, restart the netlogon and DNS Server services.
— After that convert secondary zone to primary zone.
Iterative Query: In this query the client ask the name server for the best possible answer, the name server check the cache and zone for which it’s authoritative and returns the best possible answer to the client, which would be the full answer like IP address or try the other name server
Recursive Query: Client demands either a full answer or an error message (like record or domain name does not exist)
Client machine always send recursive query to the DNS server, if the DNS server does not have the requested information, DNS server send the iterative query to the other name server (through forwarders or secondary DNS server) until it gets the information, or until the name query fails.
DNS Records: Start of Authority
The first record in a database file is the start of authority (SOA) record. The SOA defines
the general parameters for the DNS zone, including the identity of the authoritative server
for the zone.
The SOA appears in the following format:
@ IN SOA primary_mastercontact_e-mailserial_number
Here is a sample SOA from the domain hyaking.com:
@ IN SOA test.hyaking.com. hostmaster.hyaking.com.