DNS Interview Questions And Answers

DNS Interview Questions and Answer

1.                    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?

PTR Records

2.                    What is the main purpose of a DNS server?

DNS servers are used to resolve FQDN hostnames into IP addresses and vice versa

3.                    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.

4.                    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

5.                    What is the main purpose of SRV records?

SRV records are used in locating hosts that provide certain network services.

6.                    Before installing your first domain controller in the network, you installed a DNS server and created a zone, naming it as you would name your AD domain. However, after the installation of the domain controller, you are unable to locate infrastructure SRV records anywhere in the zone. What is the most likely cause of this failure?

The zone you created was not configured to allow dynamic updates. The local interface on the DNS server was not configured to allow dynamic updates.

7.                    Which of the following conditions must be satisfied to configure dynamic DNS updates for legacy clients?

The zone to be used for dynamic updates must be configured to allow dynamic updates. The DHCP server must support, and be configured to allow, dynamic updates for legacy clients.

8.                    At some point during the name resolution process, the requesting party received authoritative reply. Which further actions are likely to be taken after this reply?

After receiving the authoritative reply, the resolution process is effectively over.

9.                    Your company uses ten domain controllers, three of which are also used as DNS servers. You have one companywide AD-integrated zone, which contains several thousand resource records. This zone also allows dynamic updates, and it is critical to keep this zone up-to-date.
Replication between domain controllers takes up a significant amount of bandwidth. You are looking to cut bandwidth usage for the purpose of replication. What should you do?

Change the replication scope to all DNS servers in the domain.

10.                You are administering a network connected to the Internet. Your users complain that everything is slow. Preliminary research of the problem indicates that it takes a considerable amount of time to resolve names of resources on the Internet. What is the most likely reason for this?

DNS servers are not caching replies.. Local client computers are not caching replies… The cache.dns file may have been corrupted on the server.