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Dear Sirs,
I face a very annoying problem with client dns queries. I have manually configured a nameserver (retec.linux.bogus - 192.168.10.1) for the domain linux.bogus on RedHat 7.2. The corresponding critical sections in named.conf, linux.bogus, 192.168.10, nsswitch.conf, resolv.conf, /etc/hosts, /etc/host.conf files, on the nameserver are the following: named.conf: ----------------- zone "linux.bogus" IN { type master; file "pz/linux.bogus"; }; zone "10.168.192.in-addr.arpa" IN { type master; file "pz/192.168.10"; }; ============================== linux.bogus: --------------- $TTL 2D @ IN SOA retec.linux.bogus. root.retec.linux.bogus. ( 2002072701 2D 3H 6W 1D ) IN NS retec.linux.bogus. retec IN A 192.168.10.1 retec-2.linux.bogus. IN A 192.168.10.2 www IN CNAME retec ====================================== 192.168.10: ----------------- $TTL 2D @ IN SOA retec.linux.bogus. root.retec.linux.bogus. ( 2002072701 2D 3H 6W 1D ) IN NS retec.linux.bogus. 1 IN PTR retec.linux.bogus. 2 IN PTR retec-2.linux.bogus. =========================================== /etc/nsswitch.conf: ------------------------ hosts files dns ===================================== /etc/hosts: --------------- 127.0.0.1 localhost.localdomain localhost 192.168.10.1 retec.linux.bogus retec 192.168.10.2 retec-2.linux.bogus retec-2 ====================================== /etc/resolv.conf: ---------------------- search linux.bogus nameserver 192.168.10.1 domain linux.bogus ========================================= /etc/host.conf: ------------------- order hosts,bind =========================================== The dns name resolution on the server, works fine: Whether I ask for a hostname (retec, retec-2, www), FQDN (retec.linux.bogus, retec-2.linux.bogus, www.linux.bogus) or ip address via nslookup, dig or if telnet or ftp using any of the previous "names, IPs", sitting on the nameserver, the response is correct and IMMEDIATE (no delay experienced). The problem arises when I try some of the previous operations on the client machine! More specifically, in case I try to telnet or ftp the client itself or the nameserver, sitting on the client this time, and use the short names (retec-2, retec, www) there is a delay in the response. However this does not happen if I use the FQDNs. Moreover, I have no delays if use the nslookup utility on the client with either any of the short names or FQDNs. In that latter case the respone is immediate. The strangest of all is that if I do ftp/telnet using the short name alias "www" of the nameserver, the response is again immediate.The problem is for sure not on the topology or the cabling of the LAN (three machines on a hub.) The client and the nameserver both have two NICs but the second one is not UP. I tried to use the name service on the third machine, retec-3, which is running Windows NT 4.0 in order to verify that the problem lies on the client and not on the linux nameserver, due to the ease of the configuration of the name service, and I had the same problem exactly on the client. That is, the problem MUST BE on the client resolution. The files I used on the client are the following: /etc/hosts: ------------ 192.168.10.1 retec.linux.bogus retec 192.168.10.2 retec-2.linux.bogus retec-2 ====================================== /etc/nsswitch.conf: ----------------------- hosts files dns ==================== /etc/resolv.conf: --------------------- search linux.bogus nameserver 192.168.10.1 domain linux.bogus ========================= /etc/host.conf: ------------------ order hosts,bind ========================== /etc/sysconfig/network: -------------------------------- NETWORKING=yes HOSTNAME=retec-2.linux.bogus =============================== If I erase the contents of /etc/resolv.conf or if remove "dns" from /etc/nsswitch.conf, then only the /etc/hosts is used and the responses are ok. I have to make clear that the problem is the delay when using short names on the client. After this "short" but irritating delay,which appears only for A records - not CNAME records, the login prompt does appear. The thing is that it is not a normal resolution delay. It lasts more than that. I have read that the problem could be on the reverse zone, but it looks to me fine. I sould also mention that this problem arose when I made an "empty" custom install ( 300 MB ) on the client and configured it. Prior to this, I had already installed the name server (custom install - full) and a client (custom - full ) which I had configured as I backup (slave) name server to the first one, and as name service client to the primary name server: /etc/resolv.conf: -------------------- search linux.bogus nameserver 192.168.10.1 nameserver 192.168.10.2 domain linux.bogus ====================== At that time everything worked fine. ( After both of them were configured as name servers - I had not tried the client resolution before I had configured the secondary name server ) However, in each of the cases mentioned in this posting everything is manually configured. Please help me with this because it has driven me mad. It is so strange, to the length of my knowledge and experience of course. I am looking forward to reading from you, as it is very urgent. I am on my way to RHCE! Thank you for your time, George Raptis |
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