DNS

31. pointer record

A pointer - or PTR - record maps an IP address to a host name to allow for reverse lookup functionality.

4. When is it best to use a HOSTS file?

Because it requires a lot of maintenance, it's best when there is no other alternative. Can also be used for troubleshooting purposes or when other domain name resolution services are temporarily unavailable.

17. What are the 2 main types of DNS zone?

Primary & secondary DNS zone.

34. List the DNS name resolution process.

- A client requests name resolution, - The DNS server queries a root name server, - The root name server responds, - The DNS server queries the top-level domain server, - The DNS server queries other domain servers if necessary, - The host name is resolved, and - The resolved address is returned to the client

15. What does a DNS server store?

A DNS table for a particular zone.

14. What is a DNS zone?

A DNS zone is an area, or namespace, located within a domain over which a particular DNS server has authority.

1. What was used before DNS?

A HOSTS file was used before DNS.

21. What happens if the client queries the primary service first?

If it doesn't respond. The secondary server may handle the query.

23. How can you add records in a DNS database?

Either statically or dynamically.

2. Name resolution for a machine on the same network can be achieved by?

On the same network by a broadcast.

8. What do DNS servers do?

Store, maintain, & update parts of the database for which they have authority, & consult them when responding to requests to resolve specified host names into IP addresses.

30. name server record

The name server record - or NS record - delegates a DNS zone to use the given authoritative name servers.

13. What can a domain namespace be represented as?

Using a structure that looks like an inverted tree. It starts with a root node, which can then split into top-level domains. These top-level domains can each split into secondary domain names, which can be further divided into zone names.

18. Explain the Primary DNS Zone.

When you add a zone to a DNS server as a primary zone, that DNS server is the primary server for the zone. Only 1 DNS server can host the primary zone, & all changes to the zone must be done through that server.

19. Explain the Secondary DNS Zone.

When you add a zone to a DNS server as a secondary zone, the DNS server hosts a read-only copy of the table from the primary server. The secondary DNS zone resource records are transferred by a process known as zone transfer.

9. Name a way that FQDNs can be resolved?

With multiple DNS servers working together.

11. Name 3 components of a DNS system.

Zones, DNS & root servers, & different types of DNS records.

5. A fully qualified domain name (FQDN) must contain what?

A host & domain name.

33. Service locator record

A service locator, or SRV, record can be used to identify a host that provides a specific service, such as a web or directory services server.

32. Start of authority record

A start of authority - or SOA - record contains authoritative information for a zone, including the primary DNS name server, contact details for the domain administrator, the domain serial number, and timers relating to refreshing the zone. There can be only one SOA file for each zone.

24. Explain a static record.

A static record is entered manually by an administrator & doesn't change unless the administrator updates it.

26. Address record.

An address record - also known as an A record or host record - maps a host name to a 32-bit IPv4 address.

20. What does specifying both a primary & secondary DNS server do?

It helps increase the reliability of the name resolution service.

7. Where do DNSs store their distributed hierarchical databases?

In separate DNS servers on all networks that connect to the Internet.

12. What is a domain namespace?

Is a DNS database consisting of hierarchical grouping of domains.

10. How can a local DNS service be resolved on an internal network?

It can be resolved without the use of external DNS servers.

6. What happens if a host name is not fully qualified?

It can't be used on the Internet, since there could be any number of machines using it.

16. What do DNS root servers maintain?

Lists of all DNS servers that are authoritive for top-level domains, such as com or gov. These servers are located in secure sites around the globe.

3. Name resolution for a machine on a different network can be achieved by?

On a different network, would be by HOSTS. However, the host name entries in a HOSTS file have to be manually configured & maintained.

27. IPv6 address record

The IPv6 address record - also known as an AAAA record - maps a host name to a 128-bit IPv6 address.

22. What is the primary server returns a "Name Not Found" message?

The client's query isn't passed to a secondary server.

28. Canonical name record.

A canonical name record - more commonly known as a CNAME record or an alias record - assigns one or more aliases to a host. So it enables a single host to have more than one name. This is useful if, for example, you want to host multiple web sites on a single server with one IP address

29. Mail exchange record

A mail exchange record - also known as an MX record - identifies the device hosting a mail server. A host often has more than one mail exchanger to increase the chances that mail will reach its destination successfully. The mail exchangers are recorded in order of priority, with the mail exchanger that should be accessed first listed at the top. If the first mail exchanger is unresponsive, the second is tried, and so on.

25. How does a dynamic DNS (DDNS) work?

A network node can request to add a dynamic DNS (DDNS) record, which can change dynamically.