i386/128858: can't ping have _ character domain

[xjt]

>Number:         128858
>Category:       i386
>Synopsis:       can't ping have _ character domain
>Confidential:   no
>Severity:       non-critical
>Priority:       high
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Nov 14 03:30:06 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     xjt
>Release:        7.0-RELEASE FreeBSD
>Organization:
>Environment:
xx# uname -a
FreeBSD xx.xx 7.0-RELEASE FreeBSD 7.0-RELEASE #0: Sun Feb 24 19:59:52 UTC 2008     root at logan.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386

>Description:
xx# ping dl_dir.qq.com
ping: cannot resolve dl_dir.qq.com: Unknown server error
xx# ping custom_1.himynews.com                                        
ping: cannot resolve custom_1.himynews.com: Unknown server error
xx# ping custom_2.himynews.com                                        
ping: cannot resolve custom_2.himynews.com: Unknown server error
xx# 


can't ping if the domain have an "_" character ;

in other os is ok!

under linux
[root at test ~]# uname -a
Linux test.zytx.com 2.6.9-5.ELsmp #1 SMP Wed Jan 5 19:30:39 EST 2005 i686 i686 i386 GNU/Linux
[root at test ~]# ping dl_dir.qq.com
PING dl_dir.tc.qq.com (60.28.230.163) 56(84) bytes of data.
64 bytes from 60.28.230.163: icmp_seq=0 ttl=55 time=37.8 ms

under windows xp
C:\Documents and Settings\xx>ping dl_dir.qq.com

Pinging dl_dir.tc.qq.com [60.28.230.164] with 32 bytes of data:

Reply from 60.28.230.164: bytes=32 time=121ms TTL=54

Ping statistics for 60.28.230.164:
    Packets: Sent = 1, Received = 1, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 121ms, Maximum = 121ms, Average = 121ms
Control-C
^C
C:\Documents and Settings\xx>
>How-To-Repeat:
if domain name have an "_" character problem is happend
>Fix:
i don't known fix this bug!
in now,i am write the hostname and ip in /etc/hosts

>Release-Note:
>Audit-Trail:
>Unformatted: