DNS and Authoritative Servers


 
Thread Tools Search this Thread
Special Forums IP Networking DNS and Authoritative Servers
# 8  
Old 11-30-2013
There are two types of dns server responses: authoritative and recursive. An internet root server has all of the known IP's cached and updates them constantly. This is analogous to an NTP Level 0 server, if that helps. These root servers are always considered authoritative. Your ISP's dns is mostly recursive - i.e., it goes out and queries another dns server to get an authoritative answer.

Your ISP's dns is authoritative for nodes in its own domain (domain controller or a forest root). dns servers that are authoritative for certain domains advertise them to the outside world, i.e. internet root servers.

Code:
nslookup --type=SOA

will work in Linux as you require. I would consult the dig docset for whatever options it supports.
# 9  
Old 12-06-2013
Want recursion is a client request attribute. A server can do with 'go ash him' but a basic DNS gethostbyname library routine just wants the final answer. I suppose a DNS server might exist that can be configured to forward requests with recursion wanted. It would have a more meager cache, but if it is sharing a slow connection, it gets a quicker answer from a better connected correspondent DNS server up the chain. An absolute root server (com, net,org) might refuse to do recursion -- they are too busy as it is. Google 'DNS Recursion' and lo and behold, http://technet.microsoft.com/en-us/l.../cc771738.aspx it is an anti-DenialOfService trick to not accept recursive requests. In this case, no simple clients can connect, just other DNS servers, so you need a ring of recursion-enabled DNS servers around your simple clients. A caching no-domain DNS server is a nice thing to have as locally as possible, so you can keep asking for the same host (or address or other query) and get a local, cached answer quickly. The DNS service to support your domain (or your addresses in their pseudo domain) is really a completely separate function from a DNS server to answer queries about other domains. Caching is a dual edged sword, though, as it can be poisoned. Hackers send an unsolicited packet with bad information as if responding to a request, and the DNS server accepts and saves it. That seems a worse problem then Denial Of Service from queries to domains with infinite loops of redirection.

If there are no cache hits, a query, recursive or not, will eventually go to the authoritative source. However, any DNS server on your query's path may have a non-authoritative answer in cache to any of the multiple queries needed to finally answer your query: a.b.c.d may go to d, c.d, b.c.d to get a.b.c.d in the end.

Last edited by DGPickett; 12-06-2013 at 01:24 PM..
Login or Register to Ask a Question

Previous Thread | Next Thread

9 More Discussions You Might Find Interesting

1. Ubuntu

Network Manager not setting correct DNS servers

Since a few weeks i use Ubuntu 16 on my laptop: # uname -a Linux xxxx 4.8.0-52-generic #55~16.04.1-Ubuntu SMP Fri Apr 28 14:36:29 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux Because i want to use a custom name server i set the properties in the "Edit Connections" dialogue to the following: ... (2 Replies)
Discussion started by: bakunin
2 Replies

2. Linux

Domain registrars & DNS servers

I have read many tutorials on bind and i understand the A,MX, CNAME records. Internally, on a LAN we can install bind and create all these records and we can tell all PC and servers to use this bind as DNS server.that's fine. On the Internet, when we have purchased a valid domain like... (5 Replies)
Discussion started by: coolatt
5 Replies

3. Red Hat

DHCP & DNS - Clients get IP but don't register in DNS

I am trying to setup a CentOS 6.2 server that will be doing 3 things DHCP, DNS & Samba for a very small office (2 users). The idea being this will replace a very old Win2k server. The users are all windows based clients so only the server will be Linux based. I've installed CentOS 6.2 with... (4 Replies)
Discussion started by: FireBIade
4 Replies

4. UNIX for Advanced & Expert Users

DNS server choice: Windows DNS vs Linux BIND

I'd like to get some opnions on choosing DNS server: Windows DNS vs Linux BIND comparrsion: 1) managment, easy of use 2) Security 3) features 4) peformance 5) ?? I personally prefer Windows DNS server for management, it supports GUI and command line. But I am not sure about security... (2 Replies)
Discussion started by: honglus
2 Replies

5. IP Networking

Select DNS Servers depending on the domain

Hello, I'm using CentOS 5.3, and I connect to a VPN in order to work. The problem is that I'm constantly accessing things on the local network and the remote network. But once I'm connected to the VPN I can't access local addresses by name, I have to use the ip-address. What I'd like is to... (4 Replies)
Discussion started by: martincastell
4 Replies

6. AIX

Servers still querying old DNS server?

Hello, I've created new DNS servers and changed all of the clients /etc/resolv.conf to point to them, but when I check the old DNS logs, I see that the clients are still querying it. Does anybody know why? thanks, (2 Replies)
Discussion started by: ctcuser
2 Replies

7. AIX

Dns Servers

My only question is Can we have two auteritative Name servers for a single domain? Just a question. (1 Reply)
Discussion started by: vjm
1 Replies

8. UNIX for Dummies Questions & Answers

DNS servers

I am supposed to setup a Domain Name Server, and I don't really know how to do this, can someone either help me, or point me in the direction of a site that has a good explination of how to do this. Thanks, Ronnie (5 Replies)
Discussion started by: ignus7
5 Replies

9. UNIX for Advanced & Expert Users

How can I use DNS Server to Load Balancing my Web Servers ??

Anyone can give me some idea about DNS Server Configuration that I want to load balancing my Web Servers . (1 Reply)
Discussion started by: ottobian
1 Replies
Login or Register to Ask a Question