1)
What is DNS?
Ans: Its a distributed naming system which is organized in a hierarchy. Its used in private network or internet by computers, services or entities lying within.
2) What is Domain Naming Service?
Ans: A domain naming service translates names to IP address and vice-verse. Since humans can't remember numbers but names, this system was designed so that it helps them recognize a service or computer by name but computers are able to talk to each other using IP addresses.
3) What is forward look up?
Ans: When DNS server is queried for a name and it returns an IP address in reply, its called forward lookup. For example when I type yahoo.com in the internet explorer, the dns server returns an IP address to which a computer is able to connect.
4) What is reverse lookup?
Ans: When a DNS client queries a DNS server about an IP and the DNS server responds by providing a name is known as reverse lookup in DNS.
5) What is DNS cache?
Ans: All the queries that a DNS client does, its results are saved by it in its temporary storage so that next time when it has to find out about an IP or name, it would first look into the cache. If its not there, then only it'll contact the DNS server. This temporary storage is called DNS cache. It helps increase the speed of name resolution for frequently queried names.
Q: How DNS query works?
Ans: The answer is a detailed one. Please visit this page to know more.
6) What are DNS forwarders?
Ans: When we setup DNS servers we want queries for internet names to be forwarded to ISP DNS so that those can be resolved by the server to which they have been forwarded and returned back to my DNS server. These servers to which the DNS queries are forwarded to are called "DNS Forwarders".
Internet names are just one example, we could as well set up forwarders for a particular domain name as well.
7) What is Primary DNS Server?
Ans: Its the Writable copy of the DNS where the DNS database is stored. All the changes related to creation, deletion or modification of a DNS record or Zone is done on this server.
8) What is secondary DNS?
Ans: Secondary DNS servers are read only replica of primary DNS servers. They are created to distribute the load of primary DNS servers and to prevent the writable copy of the DNS to the external world. Secondary DNS servers do the same job of carrying out name resolution by using a read only copy of the primary DNS server database. They get this copy of primary DNS server database using one of the DNS Zone transfer methods. They are AXFR, IXFR and Full Zone Transfer.
IXFR - Incremental Zone Transfer.
AXFR - augmented Zone transfer.
Full/Complete Zone Transfer
To know more about Zone transfer in detail please visit this page and read thoroughly.
9) What is Active Directory Integrated DNS?
Ans: Active Directory–integrated DNS enables Active Directory storage and replication of DNS zone databases. Windows 2000 DNS server, the DNS server that is included with Windows 2000 Server, accommodates storing zone data in Active Directory. When you configure a computer as a DNS server, zones are usually stored as text files on name servers — that is, all of the zones required by DNS are stored in a text file on the server computer. These text files must be synchronized among DNS name servers by using a system that requires a separate replication topology and schedule called a zone transfer However, if you use Active Directory–integrated DNS when you configure a domain controller as a DNS name server, zone data is stored as an Active Directory object and is replicated as part of domain replication.
10) What is stand alone DNS Server?
Ans: A non AD integrated DNS can be termed as standalone DNS server. Its the only DNS server in an environment.
11) How DNS can do load balancing?
Ans: DNS can do load balancing by using the following methods:
1) DNS Round Robin
2) Using weights on DNS records. For example we can define weight on each MX record to define how much of load we want a particular server to handle.
12) What is Secondary Zone?
Ans: The zone hosting the read only copy of a Primary DNS server's writable copy of Zone is called a secondary zone.
13) What is SRV record?
Ans: The SRV RR identifies the host(s) that will support particular services. The MX RR is a specialised example of service discovery while the SRV RR is a general purpose RR to discover any service.
14) What is A record and PTR record?
Ans: "A" records are host records where a name is mapped to the IP address assigned to it. A "PTR" records where IP addresses are mapped to a name.
15) What is a Stub Zone?
Ans: A stub zone is a copy of a zone that contains only those resource records necessary to identify the authoritative Domain Name System (DNS) servers for that zone. A stub zone is used to resolve names between separate DNS namespaces. This type of resolution may be necessary when a corporate merger requires that the DNS servers for two separate DNS namespaces resolve names for clients in both namespaces.
A stub zone consists of:
The start of authority (SOA) resource record, name server (NS) resource records, and the glue A resource records for the delegated zone.
16) What is a delegated DNS zone? When do we use it?
Ans: Delegated DNS zones are created when we want the name resolution of subdomains or child domains to be broken up with in DNS. For more details please visit this page.
17) Steps by Step method to install DNS in Windows?
Ans: Step by step method to install DNS in windows 2003 is given here.
Step by Step method to install DNS in Windows 2008 is given here.
19) How to troubleshoot Active Directory related DNS problems using DCDiag tool?
Ans: Please find the steps here. Do look for part 2 of this youtube video.
20) New features of DNS in Windows 2008?
Ans: Its a distributed naming system which is organized in a hierarchy. Its used in private network or internet by computers, services or entities lying within.
2) What is Domain Naming Service?
Ans: A domain naming service translates names to IP address and vice-verse. Since humans can't remember numbers but names, this system was designed so that it helps them recognize a service or computer by name but computers are able to talk to each other using IP addresses.
3) What is forward look up?
Ans: When DNS server is queried for a name and it returns an IP address in reply, its called forward lookup. For example when I type yahoo.com in the internet explorer, the dns server returns an IP address to which a computer is able to connect.
4) What is reverse lookup?
Ans: When a DNS client queries a DNS server about an IP and the DNS server responds by providing a name is known as reverse lookup in DNS.
5) What is DNS cache?
Ans: All the queries that a DNS client does, its results are saved by it in its temporary storage so that next time when it has to find out about an IP or name, it would first look into the cache. If its not there, then only it'll contact the DNS server. This temporary storage is called DNS cache. It helps increase the speed of name resolution for frequently queried names.
Q: How DNS query works?
Ans: The answer is a detailed one. Please visit this page to know more.
6) What are DNS forwarders?
Ans: When we setup DNS servers we want queries for internet names to be forwarded to ISP DNS so that those can be resolved by the server to which they have been forwarded and returned back to my DNS server. These servers to which the DNS queries are forwarded to are called "DNS Forwarders".
Internet names are just one example, we could as well set up forwarders for a particular domain name as well.
7) What is Primary DNS Server?
Ans: Its the Writable copy of the DNS where the DNS database is stored. All the changes related to creation, deletion or modification of a DNS record or Zone is done on this server.
8) What is secondary DNS?
Ans: Secondary DNS servers are read only replica of primary DNS servers. They are created to distribute the load of primary DNS servers and to prevent the writable copy of the DNS to the external world. Secondary DNS servers do the same job of carrying out name resolution by using a read only copy of the primary DNS server database. They get this copy of primary DNS server database using one of the DNS Zone transfer methods. They are AXFR, IXFR and Full Zone Transfer.
IXFR - Incremental Zone Transfer.
AXFR - augmented Zone transfer.
Full/Complete Zone Transfer
To know more about Zone transfer in detail please visit this page and read thoroughly.
9) What is Active Directory Integrated DNS?
Ans: Active Directory–integrated DNS enables Active Directory storage and replication of DNS zone databases. Windows 2000 DNS server, the DNS server that is included with Windows 2000 Server, accommodates storing zone data in Active Directory. When you configure a computer as a DNS server, zones are usually stored as text files on name servers — that is, all of the zones required by DNS are stored in a text file on the server computer. These text files must be synchronized among DNS name servers by using a system that requires a separate replication topology and schedule called a zone transfer However, if you use Active Directory–integrated DNS when you configure a domain controller as a DNS name server, zone data is stored as an Active Directory object and is replicated as part of domain replication.
10) What is stand alone DNS Server?
Ans: A non AD integrated DNS can be termed as standalone DNS server. Its the only DNS server in an environment.
11) How DNS can do load balancing?
Ans: DNS can do load balancing by using the following methods:
1) DNS Round Robin
2) Using weights on DNS records. For example we can define weight on each MX record to define how much of load we want a particular server to handle.
12) What is Secondary Zone?
Ans: The zone hosting the read only copy of a Primary DNS server's writable copy of Zone is called a secondary zone.
13) What is SRV record?
Ans: The SRV RR identifies the host(s) that will support particular services. The MX RR is a specialised example of service discovery while the SRV RR is a general purpose RR to discover any service.
14) What is A record and PTR record?
Ans: "A" records are host records where a name is mapped to the IP address assigned to it. A "PTR" records where IP addresses are mapped to a name.
15) What is a Stub Zone?
Ans: A stub zone is a copy of a zone that contains only those resource records necessary to identify the authoritative Domain Name System (DNS) servers for that zone. A stub zone is used to resolve names between separate DNS namespaces. This type of resolution may be necessary when a corporate merger requires that the DNS servers for two separate DNS namespaces resolve names for clients in both namespaces.
A stub zone consists of:
The start of authority (SOA) resource record, name server (NS) resource records, and the glue A resource records for the delegated zone.
16) What is a delegated DNS zone? When do we use it?
Ans: Delegated DNS zones are created when we want the name resolution of subdomains or child domains to be broken up with in DNS. For more details please visit this page.
17) Steps by Step method to install DNS in Windows?
Ans: Step by step method to install DNS in windows 2003 is given here.
Step by Step method to install DNS in Windows 2008 is given here.
19) How to troubleshoot Active Directory related DNS problems using DCDiag tool?
Ans: Please find the steps here. Do look for part 2 of this youtube video.
20) New features of DNS in Windows 2008?
·
Background zone
loading: DNS servers that host large DNS zones that are stored in Active
Directory Domain Services (AD DS) are able to respond to client queries
more quickly when they restart because zone data is now loaded in the
background.
·
IP version 6
(IPv6) support: The DNS Server service now fully supports the longer addresses
of the IPv6 specification.
·
Support for read-only
domain controllers (RODCs): The DNS Server role in Windows Server 2008
provides primary read-only zones on RODCs.
·
Global single names:
The GlobalNames zone provides single-label name resolution for large enterprise
networks that do not deploy Windows Internet Name Service (WINS). The
GlobalNames zone is useful when using DNS name suffixes to provide single-label
name resolution is not practical.
·
Global query block
list: Clients of such protocols as the Web Proxy Auto-Discovery Protocol (WPAD)
and the Intra-site Automatic Tunnel Addressing Protocol (ISATAP) that rely on
DNS name resolution to resolve well-known host names are vulnerable to malicious
users who use dynamic update to register host computers that pose as legitimate
servers. The DNS Server role in Windows Server 2008 provides a global
query block list that can help reduce this vulnerability.
Watch the videos and have fun learning answers to the above mentioned questions and gain much more additional knowledge as well. Hope it helps you all.
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What is EDNS?
Its called "Extended mechanisms for DNS". More details can be found at the links given below:
http://spanougakis.wordpress.com/2011/05/01/edns-what-is-all-about-2/
http://social.technet.microsoft.com/Forums/en-US/winservergen/thread/b4e22807-a4ed-4a9e-be23-cdcc2b77ed22/
http://sysadminthings.blogspot.ca/2011/09/things-i-never-knew-about-dns-edns.html
Q: When does DNS works using UDP and when it uses TCP?
Ans: DNS uses both TCP and UDP for valid reasons. Note that UDP messages are not larger than 512 Bytes and are trucncted when greater than this size. So DNS uses TCP for Zone transfer and UDP for name queries either regular (primary) or reverse. UDP can be used to exchange small information whereas TCP must be used to exchange information larger than 512 bytes. If a client doesn't get response from DNS it must retransmit the data using TCP after 3-5 seconds of interval.
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