> What is DNS ?
The Domain Name System (DNS) is a hierarchical distributed naming system for computers. The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain. Authoritative name servers are assigned to be responsible for their particular domains, and in turn can assign other authoritative name servers for their sub-domains.
>What is the main purpose of a DNS server? DNS servers are used to resolve FQDN hostnames into IP addresses and vice versa.
>What is the port no of dns ?
>What is a Forward Lookup?
Resolving Host Names to IP Addresses.
>What is Reverse Lookup?
Reverse DNS turns an IP address into a hostname. Example, it might turn 18.104.22.168 into host.example.com.
>What is a Resource Record?
It is a record provides the information about the resources available in the N/W infrastructure.
>What is a Zone?
A DNS zone is the contiguous portion of the DNS domain name space over which a DNS server has authority. A zone is a portion of a namespace. A zone contains the resource records for all of the names within the particular zone. Zone files are used if DNS data if not integrated with Active Directory. The zone files contain the DNS database resource records that define the zone. If DNS and Active Directory are integrated, then DNS data is stored in Active Directory.
> What are the different types of Zones in DNS ?
The DNS Server service provides for three types of zones:
1. Primary zone
2. Secondary zone
3. Stub zone
4. Active Directory-integrated zone
> Explain Primary zone ?
A primary zone is the only zone type that can be edited or updated because the data in the zone is the original source of the data for all domains in the zone. Updates made to the primary zone are made by the DNS server that is authoritative for the specific primary zone.
> Explain Secondary zone ?
A secondary zone is a read-only copy of the zone that was copied from the master server during zone transfer. In fact, a secondary zone can only be updated through zone transfer.
> Explain Stub zone ?
Stub zones only contain those resource records necessary to identify the authoritative DNS servers for the master zone. Stub zones therefore contain only a copy of a zone, and are used to resolve recursive and iterative queries.
> Explain Active Directory-integrated zone ?
An Active Directory-integrated zone is a zone that stores its data in Active Directory. DNS zone files are not needed. This type of zone is an authoritative primary zone. An Active Directory-integrated zone’s zone data is replicated during the Active Directory replication process. Active Directory-integrated zones also enjoy the Active Directory’s security features.
>Secure services in your network require reverse name resolution to make it more difficult to launch successful attacks against the services. To set this up, you configure a reverse lookup zone and proceed to add records. Which record types do you need to create?
>SOA records must be included in every zone. What are they used for ? SOA records contain a TTL value, used by default in all resource records in the zone. SOA records contain the e-mail address of the person who is responsible for maintaining the zone. SOA records contain the current serial number of the zone, which is used in zone transfers.
>By default, if the name is not found in the cache or local hosts file, what is the first step the client takes to resolve the FQDN name into an IP address ? Performs a recursive search through the primary DNS server based on the network interface configuration .
> On which port DNS server works ?
DNS servers use port 53 by default. Incoming and outgoing packets should be allowed on port 53. Also allow connections on port 921 if you configure a lightweight resolver server.
The DNS control utility, rndc, connects to the DNS server with TCP port 953 by default. If you are running rndc on the name server, connections on this TCP port from localhost should be allowed. If you are running rndc on additional systems, allow connections to port 953 (or whatever port you have chosen to configure) from these additional systems.
> What is round robin DNS?
Round robin DNS is usually used for balancing the load of geographically distributed Web servers. For example, a company has one domain name and three identical home pages residing on three servers with three different IP addresses. When one user accesses the home page it will be sent to the first IP address.
The second user who accesses the home page will be sent to the next IP address, and the third user will be sent to the third IP address. In each case, once the IP address is given out, it goes to the end of the list. The fourth user, therefore, will be sent to the first IP address, and so forth.